The Battle of the Atlantic, the longest continuous
military campaign
A military campaign is large-scale long-duration significant military strategy plan incorporating a series of interrelated military operations or battles forming a distinct part of a larger conflict often called a war. The term derives from the ...
in
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, ran from 1939 to the
defeat of Nazi Germany
The final battle of the European Theatre of World War II continued after the definitive overall surrender of Nazi Germany to the Allies, signed by Field marshal Wilhelm Keitel on 8 May 1945 in Karlshorst, Berlin. After German dictator Adolf H ...
in 1945, covering a major part of the
naval history of World War II
At the beginning of World War II, the Royal Navy was the strongest navy in the world, with the largest number of warships built and with naval bases across the globe. It had over 15 battleships and battlecruisers, 7 aircraft carriers, 66 cruisers ...
. At its core was the
Allied
An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...
naval
blockade of Germany
The Blockade of Germany, or the Blockade of Europe, occurred from 1914 to 1919. The prolonged naval blockade was conducted by the Allies of World War I, Allies during and after World War I in an effort to restrict the maritime supply of goods t ...
, announced the day after the declaration of war, and Germany's subsequent counter-blockade. The campaign peaked from mid-1940 through to the end of 1943.
The Battle of the Atlantic pitted
U-boat
U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role ...
s and other warships of the German ''
Kriegsmarine
The (, ) was the navy of Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war (1919–1935) of the Weimar Republic. The was one of three official branches, along with the a ...
'' (Navy) and aircraft of the ''
Luftwaffe
The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabtei ...
'' (Air Force) against the
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
,
Royal Canadian Navy
The Royal Canadian Navy (RCN; french: Marine royale canadienne, ''MRC'') is the Navy, naval force of Canada. The RCN is one of three environmental commands within the Canadian Armed Forces. As of 2021, the RCN operates 12 frigates, four attack s ...
,
United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
, and
Allied merchant shipping.
Convoy
A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support and can help maintain cohesion within a unit. It may also be used ...
s, coming mainly from North America and predominantly going to the United Kingdom and the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
, were protected for the most part by the British and Canadian navies and air forces. These forces were aided by ships and aircraft of the United States beginning September 13, 1941.
[ Carney, Robert B., Admiral, USN. "Comment and Discussion" ''United States Naval Institute Proceedings'' January 1976, p.74. Admiral Carney was assistant chief of staff and operations officer to Admiral ]Arthur L. Bristol
Arthur LeRoy Bristol, Jr. (July 15, 1886 – April 27, 1942) was a vice admiral in the United States Navy, who held important commands during World War I and World War II, and was an early aircraft carrier commander.
Early life and career
B ...
, commander of the support force of United States ships and planes providing North Atlantic trade convoy escort services. This support force was designated Task Force 24 after the declaration of war. The Germans were joined by
submarine
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
s of the Italian ''
Regia Marina
The ''Regia Marina'' (; ) was the navy of the Kingdom of Italy (''Regno d'Italia'') from 1861 to 1946. In 1946, with the Italian constitutional referendum, 1946, birth of the Italian Republic (''Repubblica Italiana''), the ''Regia Marina'' ch ...
'' (Royal Navy) after Germany's
Axis
An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to:
Mathematics
* Axis of rotation: see rotation around a fixed axis
*Axis (mathematics), a designator for a Cartesian-coordinate ...
ally
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
entered the war on June 10, 1940.
As an island country, the United Kingdom was highly dependent on imported goods. Britain required more than a million tons of imported material per week in order to survive and fight. In essence, the Battle of the Atlantic involved a
tonnage war
A tonnage war is a military strategy aimed at merchant shipping. The premise is that the enemy has a finite number of ships and a finite capacity to build replacements. The concept was made famous by German Grand Admiral Karl Dönitz, who wrote:"T ...
: the Allied struggle to supply Britain and the Axis attempt to stem the flow of merchant shipping that enabled Britain to keep fighting.
Rationing in the United Kingdom
Rationing was introduced temporarily by the British government several times during the 20th century, during and immediately after a war.
At the start of the Second World War in 1939, the United Kingdom was importing 20 million long tons of ...
was also used with the aim of reducing demand, by reducing wastage and increasing domestic production and equality of distribution. From 1942 onward the Axis also sought to prevent the build-up of Allied supplies and equipment in the
British Isles
The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...
in preparation for the
invasion of occupied Europe. The defeat of the U-boat threat was a prerequisite for pushing back the Axis in Western Europe. The outcome of the battle was a strategic victory for the Allies—the German blockade failed—but at great cost: 3,500 merchant ships and 175 warships were sunk in the Atlantic for the loss of 783 U-boats (the majority of them
Type VII submarine
Type VII U-boats were the most common type of German World War II U-boat. 703 boats were built by the end of the war. The lone surviving example, , is on display at the Laboe Naval Memorial located in Laboe, Schleswig-Holstein, Germany.
Con ...
s) and 47 German surface warships, including 4 battleships (, , , and ), 9 cruisers, 7 raiders, and 27 destroyers. Of the U-boats, 519 were sunk by British, Canadian, or other allied forces, while 175 were destroyed by American forces; 15 were destroyed by the Soviets and 73 were scuttled by their crews before the end of the war for various reasons.
This front ended up being highly significant for the German war effort: Germany spent more money on producing naval vessels than it did every type of ground vehicle combined, including tanks.
United States Strategic Bombing Survey
The United States Strategic Bombing Survey (USSBS) was a written report created by a board of experts assembled to produce an impartial assessment of the effects of the Anglo-American strategic bombing of Nazi Germany during the European theatre o ...
Vol 3, ''Effects of Strategic Bombing on the German War Economy'', 1945, p. 144.
The Battle of the Atlantic has been called the "longest, largest, and most complex" naval battle in history. The campaign started immediately after the European War began, during the so-called "
Phoney War
The Phoney War (french: Drôle de guerre; german: Sitzkrieg) was an eight-month period at the start of World War II, during which there was only one limited military land operation on the Western Front, when French troops invaded Germ ...
", and lasted more than five years, until the
German surrender
The German Instrument of Surrender (german: Bedingungslose Kapitulation der Wehrmacht, lit=Unconditional Capitulation of the "Wehrmacht"; russian: Акт о капитуляции Германии, Akt o kapitulyatsii Germanii, lit=Act of capit ...
in May 1945. It involved thousands of ships in more than 100 convoy battles and perhaps 1,000 single-ship encounters, in a theatre covering millions of square miles of ocean. The situation changed constantly, with one side or the other gaining advantage, as participating countries surrendered, joined and even changed sides in the war, and as new weapons, tactics, counter-measures and equipment were developed by both sides. The Allies gradually gained the upper hand, overcoming German surface-raiders by the end of 1942 and defeating the U-boats by mid-1943, though losses due to U-boats continued until the war's end. British Prime Minister
Winston Churchill
Sir Winston Leonard Spencer Churchill (30 November 187424 January 1965) was a British statesman, soldier, and writer who served as Prime Minister of the United Kingdom twice, from 1940 to 1945 Winston Churchill in the Second World War, dur ...
later wrote "The only thing that really frightened me during the war was the U-boat peril. I was even more anxious about this battle than I had been about the glorious air fight called the '
Battle of Britain
The Battle of Britain, also known as the Air Battle for England (german: die Luftschlacht um England), was a military campaign of the Second World War, in which the Royal Air Force (RAF) and the Fleet Air Arm (FAA) of the Royal Navy defende ...
'."
Name
On 5 March 1941,
First Lord of the Admiralty
The First Lord of the Admiralty, or formally the Office of the First Lord of the Admiralty, was the political head of the English and later British Royal Navy. He was the government's senior adviser on all naval affairs, responsible for the di ...
A. V. Alexander
Albert Victor Alexander, 1st Earl Alexander of Hillsborough, (1 May 1885 – 11 January 1965), was a British Labour and Co-operative politician. He was three times First Lord of the Admiralty, including during the Second World War, and then Mi ...
asked
Parliament
In modern politics, and history, a parliament is a legislative body of government. Generally, a modern parliament has three functions: Representation (politics), representing the Election#Suffrage, electorate, making laws, and overseeing ...
for "many more ships and great numbers of men" to fight "the Battle of the Atlantic", which he compared to the
Battle of France
The Battle of France (french: bataille de France) (10 May – 25 June 1940), also known as the Western Campaign ('), the French Campaign (german: Frankreichfeldzug, ) and the Fall of France, was the Nazi Germany, German invasion of French Third Rep ...
, fought the previous summer. The first meeting of the
Cabinet's "Battle of the Atlantic Committee" was on March 19. Churchill claimed to have coined the phrase "Battle of the Atlantic" shortly before Alexander's speech, but there are several examples of earlier usage.
Background
Following the use of
unrestricted submarine warfare
Unrestricted submarine warfare is a type of naval warfare in which submarines sink merchant ships such as freighters and tankers without warning, as opposed to attacks per prize rules (also known as "cruiser rules") that call for warships to sea ...
by Germany in the
First World War
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, countries tried to limit or abolish submarines. The effort failed. Instead, the
London Naval Treaty
The London Naval Treaty, officially the Treaty for the Limitation and Reduction of Naval Armament, was an agreement between the United Kingdom, Japan, France, Italy, and the United States that was signed on 22 April 1930. Seeking to address is ...
required submarines to abide by "
cruiser rules
Cruiser rules is a colloquial phrase referring to the conventions regarding the attacking of a merchant ship by an armed vessel. Here ''cruiser'' is meant in its original meaning of a ship sent on an independent mission such as commerce raiding. ...
", which demanded they surface, search and place ship crews in "a place of safety" (for which lifeboats did not qualify, except under particular circumstances) before sinking them, unless the ship in question showed "persistent refusal to stop...or active resistance to visit or search". These regulations did not prohibit arming merchantmen,
but doing so, or having them report contact with submarines (or
raiders), made them ''de facto'' naval auxiliaries and removed the protection of the cruiser rules.
[Dönitz, Karl. ''Memoirs: Ten Years and Twenty Days''; von der Poorten, Edward P. ''The German Navy in World War II'' (T. Y. Crowell, 1969); Milner, Marc. ''North Atlantic run : the Royal Canadian Navy and the battle for the convoys'' (Vanwell Publishing, 2006)] This made restrictions on submarines effectively moot.
Early skirmishes (September 1939 – May 1940)
In 1939, the ''Kriegsmarine'' lacked the strength to challenge the combined British Royal Navy and
French Navy
The French Navy (french: Marine nationale, lit=National Navy), informally , is the maritime arm of the French Armed Forces and one of the five military service branches of France. It is among the largest and most powerful naval forces in t ...
(''Marine Nationale'') for command of the sea. Instead, German naval strategy relied on commerce raiding using
capital ship
The capital ships of a navy are its most important warships; they are generally the larger ships when compared to other warships in their respective fleet. A capital ship is generally a leading or a primary ship in a naval fleet.
Strategic im ...
s,
armed merchant cruiser
An armed merchantman is a merchant ship equipped with guns, usually for defensive purposes, either by design or after the fact. In the days of sail, piracy and privateers, many merchantmen would be routinely armed, especially those engaging in lo ...
s, submarines and aircraft. Many German warships were already at sea when war was declared in September 1939, including most of the available U-boats and the "
pocket battleship
The ''Deutschland'' class was a series of three ''Panzerschiffe'' (armored ships), a form of heavily armed cruiser, built by the ''Reichsmarine'' officially in accordance with restrictions imposed by the Treaty of Versailles. The ships of the cl ...
s" (''Panzerschiffe'') and which had sortied into the Atlantic in August. These ships immediately attacked British and French shipping. sank the
ocean liner
An ocean liner is a passenger ship primarily used as a form of transportation across seas or oceans. Ocean liners may also carry cargo or mail, and may sometimes be used for other purposes (such as for pleasure cruises or as hospital ships).
Ca ...
within hours of the declaration of war—in breach of her orders not to sink passenger ships. The U-boat fleet, which was to dominate so much of the Battle of the Atlantic, was small at the beginning of the war; many of the 57 available U-boats were the small and short-range
Type IIs, useful primarily for
minelaying
A minelayer is any warship, submarine or military aircraft deploying explosive mines. Since World War I the term "minelayer" refers specifically to a naval ship used for deploying naval mines. "Mine planting" was the term for installing controll ...
and operations in British coastal waters. Much of the early German anti-shipping activity involved minelaying by
destroyer
In naval terminology, a destroyer is a fast, manoeuvrable, long-endurance warship intended to escort
larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers. They were originally developed in ...
s, aircraft and U-boats off British ports.
With the outbreak of war, the British and French immediately began a
blockade of Germany
The Blockade of Germany, or the Blockade of Europe, occurred from 1914 to 1919. The prolonged naval blockade was conducted by the Allies of World War I, Allies during and after World War I in an effort to restrict the maritime supply of goods t ...
, although this had little immediate effect on German industry. The Royal Navy quickly introduced a
convoy system
A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support and can help maintain cohesion within a unit. It may also be used ...
for the protection of trade that gradually extended out from the British Isles, eventually reaching as far as
Panama
Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...
,
Bombay
Mumbai (, ; also known as Bombay — the official name until 1995) is the capital city of the Indian state of Maharashtra and the ''de facto'' financial centre of India. According to the United Nations, as of 2018, Mumbai is the second- ...
and
Singapore
Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...
. When the convoy system was first introduced however, Britain's Royal Admiralty strongly opposed the idea. Britain believed that the convoy would be a waste of ships that they could not afford to do, considering they might be needed in battle. Convoys allowed the Royal Navy to concentrate its escorts near the one place the U-boats were guaranteed to be found, the convoys. Each convoy consisted of between 30 and 70 mostly unarmed merchant ships.
Some British naval officials, particularly the First Lord of the Admiralty,
Winston Churchill
Sir Winston Leonard Spencer Churchill (30 November 187424 January 1965) was a British statesman, soldier, and writer who served as Prime Minister of the United Kingdom twice, from 1940 to 1945 Winston Churchill in the Second World War, dur ...
, sought a more 'offensive' strategy. The Royal Navy formed anti-submarine hunting groups based on
aircraft carrier
An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a ...
s to patrol the shipping lanes in the
Western Approaches
The Western Approaches is an approximately rectangular area of the Atlantic Ocean lying immediately to the west of Ireland and parts of Great Britain. Its north and south boundaries are defined by the corresponding extremities of Britain. The c ...
and hunt for German U-boats. This strategy was deeply flawed because a U-boat, with its tiny silhouette, was always likely to spot the surface warships and submerge long before it was sighted. The carrier aircraft were little help; although they could spot submarines on the surface, at this stage of the war they had no adequate weapons to attack them, and any submarine found by an aircraft was long gone by the time surface warships arrived. The hunting group strategy proved a disaster within days. On 14 September 1939, Britain's most modern carrier, , narrowly avoided being sunk when three torpedoes from exploded prematurely. ''U-39'' was forced to surface and scuttle by the escorting destroyers, becoming the first U-boat loss of the war. Another carrier, , was sunk three days later by .
Escort destroyers hunting for U-boats continued to be a prominent, but misguided, technique of British anti-submarine strategy for the first year of the war. U-boats nearly always proved elusive, and the convoys, denuded of cover, were put at even greater risk.
German success in sinking ''Courageous'' was surpassed a month later when
Günther Prien
Günther Prien (16 January 1908 – presumed 8 March 1941) was a German U-boat commander during World War II. He was the first U-boat commander to receive the Knight's Cross of the Iron Cross and the first member of the ''Kriegsmarine'' to r ...
in penetrated the British base at
Scapa Flow
Scapa Flow viewed from its eastern end in June 2009
Scapa Flow (; ) is a body of water in the Orkney Islands, Scotland, sheltered by the islands of Mainland, Graemsay, Burray,S. C. George, ''Jutland to Junkyard'', 1973. South Ronaldsay and ...
and sank the old battleship at anchor, immediately becoming a hero in Germany.
In the South Atlantic, British forces were stretched by the cruise of ''Admiral Graf Spee'', which sank nine merchant ships of in the South Atlantic and Indian Ocean during the first three months of war. The British and French formed a series of hunting groups including three
battlecruiser
The battlecruiser (also written as battle cruiser or battle-cruiser) was a type of capital ship of the first half of the 20th century. These were similar in displacement, armament and cost to battleships, but differed in form and balance of attr ...
s, three aircraft carriers, and 15 cruisers to seek the raider and her sister ''Deutschland'', which was operating in the North Atlantic. These hunting groups had no success until ''Admiral Graf Spee'' was
caught off the mouth of the River Plate between
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
and
Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
by an inferior British force. After suffering damage in the subsequent action, she took shelter in neutral
Montevideo
Montevideo () is the Capital city, capital and List of cities in Uruguay, largest city of Uruguay. According to the 2011 census, the city proper has a population of 1,319,108 (about one-third of the country's total population) in an area of . M ...
harbour and was
scuttled
Scuttling is the deliberate sinking of a ship. Scuttling may be performed to dispose of an abandoned, old, or captured vessel; to prevent the vessel from becoming a navigation hazard; as an act of self-destruction to prevent the ship from being ...
on 17 December 1939.
After this initial burst of activity, the Atlantic campaign quieted down. Admiral
Karl Dönitz
Karl Dönitz (sometimes spelled Doenitz; ; 16 September 1891 24 December 1980) was a German admiral who briefly succeeded Adolf Hitler as head of state in May 1945, holding the position until the dissolution of the Flensburg Government follo ...
, commander of the U-boat fleet, had planned a maximum submarine effort for the first month of the war, with almost all the available U-boats out on patrol in September. That level of deployment could not be sustained; the boats needed to return to harbour to refuel, re-arm, re-stock supplies, and refit. The harsh winter of 1939–40, which froze over many of the Baltic ports, seriously hampered the German offensive by trapping several new U-boats in the ice.
Hitler's
Adolf Hitler (; 20 April 188930 April 1945) was an Austrian-born German politician who was dictator of Nazi Germany, Germany from 1933 until Death of Adolf Hitler, his death in 1945. Adolf Hitler's rise to power, He rose to power as the le ...
plans to invade Norway and Denmark in the spring of 1940 led to the withdrawal of the fleet's surface warships and most of the ocean-going U-boats for fleet operations in
Operation Weserübung
Operation Weserübung (german: Unternehmen Weserübung , , 9 April – 10 June 1940) was Germany's assault on Denmark and Norway during the Second World War and the opening operation of the Norwegian Campaign.
In the early morning of 9 Ap ...
.
The resulting
Norwegian campaign revealed serious flaws in the
magnetic influence pistol (firing mechanism) of the U-boats' principal weapon, the
torpedo
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, su ...
. Although the narrow fjords gave U-boats little room for manoeuvre, the concentration of British warships, troopships and supply ships provided countless opportunities for the U-boats to attack. Time and again, U-boat captains tracked British targets and fired, only to watch the ships sail on unharmed as the torpedoes exploded prematurely (due to the influence pistol), or hit and failed to explode (because of a faulty contact pistol), or ran beneath the target without exploding (due to the influence feature or depth control not working correctly). Not a single British warship was sunk by a U-boat in more than 20 attacks. As the news spread through the U-boat fleet, it began to
undermine morale. The director in charge of torpedo development continued to claim it was the crews' fault. In early 1941, the problems were determined to be due to differences in the earth's magnetic fields at high latitudes and a slow leakage of high-pressure air from the submarine into the torpedo's depth regulation gear. These problems were solved by about March 1941, making the torpedo a formidable weapon. Similar problems plagued the US Navy's
Mark 14 torpedo
The Mark 14 torpedo was the United States Navy's standard submarine-launched anti-ship torpedo of World War II. This weapon was plagued with many problems which crippled its performance early in the war. It was supplemented by the Mark 18 elec ...
. The US ignored reports of German problems.
Submarine warfare
Early in the war, Dönitz submitted a memorandum to Grand Admiral
Erich Raeder
Erich Johann Albert Raeder (24 April 1876 – 6 November 1960) was a German admiral who played a major role in the naval history of World War II. Raeder attained the highest possible naval rank, that of grand admiral, in 1939, becoming the fir ...
, the German navy's Commander-in-Chief, in which he estimated effective submarine warfare could bring Britain to its knees because of the country's dependence on overseas commerce. He advocated a system known as the ''Rudeltaktik'' (the so-called "
wolf pack
A pack is a social group of conspecific canines. Packs aren't formed by all canines, especially small sized canines like the Red fox. The number of members in a pack and their social behavior varies from species to species. Social structure is v ...
"), in which U-boats would spread out in a long line across the projected course of a convoy. Upon sighting a target, they would come together to attack ''en masse'' and overwhelm any escorting warships. While escorts chased individual submarines, the rest of the "pack" would be able to attack the merchant ships with impunity. Dönitz calculated 300 of the latest ''Atlantic Boats'' (the
Type VII), would create enough havoc among Allied shipping that Britain would be knocked out of the war.
![11 H](https://upload.wikimedia.org/wikipedia/commons/7/78/11_H.M._Transport_Porto_at_Murmansk.jpg)
This was in stark contrast to the traditional view of submarine deployment up until then, in which the submarine was seen as a lone ambusher, waiting outside an enemy port to attack ships entering and leaving. This had been a very successful tactic used by British submarines in the Baltic and
Bosporus
The Bosporus Strait (; grc, Βόσπορος ; tr, İstanbul Boğazı 'Istanbul strait', colloquially ''Boğaz'') or Bosphorus Strait is a natural strait and an internationally significant waterway located in Istanbul in northwestern T ...
during World War I, but it could not be successful if port approaches were well patrolled. There had also been naval theorists who held that submarines should be attached to a fleet and used like destroyers; this had been tried by the Germans at
Jutland
Jutland ( da, Jylland ; german: Jütland ; ang, Ēota land ), known anciently as the Cimbric or Cimbrian Peninsula ( la, Cimbricus Chersonesus; da, den Kimbriske Halvø, links=no or ; german: Kimbrische Halbinsel, links=no), is a peninsula of ...
with poor results, since underwater communications were in their infancy. (Interwar exercises had proven the idea faulty.) The
Japanese
Japanese may refer to:
* Something from or related to Japan, an island country in East Asia
* Japanese language, spoken mainly in Japan
* Japanese people, the ethnic group that identifies with Japan through ancestry or culture
** Japanese diaspor ...
also adhered to the idea of a fleet submarine, following the
doctrine
Doctrine (from la, doctrina, meaning "teaching, instruction") is a codification of beliefs or a body of teachings or instructions, taught principles or positions, as the essence of teachings in a given branch of knowledge or in a belief system ...
of
Mahan Mahan or Mahaan may refer to:
* Mahan (name)
* Mahan confederacy, chiefdoms in ancient Korea
* Mahan, Iran, a city in Kerman Province
* Mahan District, an administrative subdivision of Kerman Province
* Mahan Rural District, an administrative subdi ...
, and never used their submarines either for close blockade or convoy
interdiction Interdiction is a military term for the act of delaying, disrupting, or destroying enemy forces or supplies en route to the battle area. A distinction is often made between strategic and tactical interdiction. The former refers to operations whose e ...
. The submarine was still looked upon by much of the naval world as "dishonourable", compared to the prestige attached to capital ships. This was true in the ''Kriegsmarine'' as well; Raeder successfully lobbied for the money to be spent on capital ships instead.
The Royal Navy's main anti-submarine weapon before the war was the inshore patrol craft, which was fitted with
hydrophone
A hydrophone ( grc, ὕδωρ + φωνή, , water + sound) is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potenti ...
s and armed with a small gun and depth charges. The Royal Navy, like most, had not considered
anti-submarine warfare
Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are t ...
as a tactical subject during the 1920s and 1930s. Unrestricted submarine warfare had been outlawed by the London Naval Treaty; anti-submarine warfare was seen as 'defensive' rather than dashing; many naval officers believed anti-submarine work was drudgery similar to
mine sweeping
Minesweeping is the practice of the removal of explosive naval mines, usually by a specially designed ship called a minesweeper using various measures to either capture or detonate the mines, but sometimes also with an aircraft made for that ...
; and
ASDIC
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or ...
was believed to have rendered submarines impotent. Although destroyers also carried depth charges, it was expected these ships would be used in fleet actions rather than coastal patrol, so they were not extensively trained in their use. The British, however, ignored the fact that arming merchantmen, as Britain did from the start of the war, removed them from the protection of the "
cruiser rules
Cruiser rules is a colloquial phrase referring to the conventions regarding the attacking of a merchant ship by an armed vessel. Here ''cruiser'' is meant in its original meaning of a ship sent on an independent mission such as commerce raiding. ...
",
and the fact that anti-submarine trials with ASDIC had been conducted in ideal conditions.
British situation
The German occupation of Norway in April 1940, the rapid conquest of the
Low Countries
The term Low Countries, also known as the Low Lands ( nl, de Lage Landen, french: les Pays-Bas, lb, déi Niddereg Lännereien) and historically called the Netherlands ( nl, de Nederlanden), Flanders, or Belgica, is a coastal lowland region in N ...
and
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
in May and June, and the Italian entry into the war on the Axis side in June transformed the war at sea in general and the Atlantic campaign in particular in three main ways:
* Britain lost its biggest ally. In 1940, the French Navy was the fourth largest in the world. Only a handful of French ships joined the
Free French Forces
__NOTOC__
The French Liberation Army (french: Armée française de la Libération or AFL) was the reunified French Army that arose from the merging of the Armée d'Afrique with the prior Free French Forces (french: Forces françaises libres, l ...
and fought against Germany, though these were later joined by a few Canadian
destroyer
In naval terminology, a destroyer is a fast, manoeuvrable, long-endurance warship intended to escort
larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers. They were originally developed in ...
s. With the French fleet removed from the campaign, the Royal Navy was stretched even further. Italy's declaration of war meant that Britain also had to reinforce the
Mediterranean Fleet
The British Mediterranean Fleet, also known as the Mediterranean Station, was a formation of the Royal Navy. The Fleet was one of the most prestigious commands in the navy for the majority of its history, defending the vital sea link between t ...
and establish a new group at
Gibraltar
)
, anthem = " God Save the King"
, song = " Gibraltar Anthem"
, image_map = Gibraltar location in Europe.svg
, map_alt = Location of Gibraltar in Europe
, map_caption = United Kingdom shown in pale green
, mapsize =
, image_map2 = Gib ...
, known as
Force H
Force H was a British naval formation during the Second World War. It was formed in 1940, to replace French naval power in the western Mediterranean removed by the French armistice with Nazi Germany. The force occupied an odd place within the ...
, to replace the French fleet in the Western Mediterranean.
* The U-boats gained direct access to the Atlantic. Since the
English Channel
The English Channel, "The Sleeve"; nrf, la Maunche, "The Sleeve" (Cotentinais) or ( Jèrriais), (Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Kana ...
was relatively shallow, and was partially blocked with minefields by mid-1940, U-boats were ordered not to negotiate it and instead travel around the British Isles to reach the most profitable spot to hunt ships. The German bases in France at
Brest
Brest may refer to:
Places
*Brest, Belarus
**Brest Region
**Brest Airport
**Brest Fortress
*Brest, Kyustendil Province, Bulgaria
*Břest, Czech Republic
*Brest, France
**Arrondissement of Brest
**Brest Bretagne Airport
** Château de Brest
*Brest, ...
,
Lorient
Lorient (; ) is a town (''Communes of France, commune'') and Port, seaport in the Morbihan Departments of France, department of Brittany (administrative region), Brittany in western France.
History
Prehistory and classical antiquity
Beginn ...
, and
La Pallice
La Pallice (also known as ''grand port maritime de La Rochelle'') is the commercial deep-water port of La Rochelle, France.
During the Fall of France, on 19 June 1940, approximately 6,000 Polish soldiers in exile under the command of Stanisław ...
(near
La Rochelle
La Rochelle (, , ; Poitevin-Saintongeais: ''La Rochéle''; oc, La Rochèla ) is a city on the west coast of France and a seaport on the Bay of Biscay, a part of the Atlantic Ocean. It is the capital of the Charente-Maritime department. With ...
), were about closer to the Atlantic than the bases on the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
. This greatly improved the situation for U-boats in the Atlantic, enabling them to attack convoys further west and letting them spend longer time on patrol, doubling the effective size of the U-boat force. The Germans later built huge fortified concrete
submarine pen
A submarine pen (''U-Boot-Bunker'' in German) is a type of submarine base that acts as a bunker to protect submarines from air attack.
The term is generally applied to submarine bases constructed during World War II, particularly in Germany and ...
s for the U-boats in the French Atlantic bases, which were impervious to Allied bombing until mid-1944 when the
Tallboy bomb
Tallboy or Bomb, Medium Capacity, 12,000 lb was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and used by the Royal Air Force (RAF) during the Second World War."Medium capacity" refers to the ratio of bomb ...
became available. From early July, U-boats returned to the new French bases when they had completed their Atlantic patrols.
* British destroyers were diverted from the Atlantic. The
Norwegian campaign and the
German invasion of the Low Countries and France imposed a heavy strain on the Royal Navy's destroyer flotillas. Many older destroyers were withdrawn from convoy routes to support the Norwegian campaign in April and May and then diverted to the English Channel to support the withdrawal from Dunkirk. By the summer of 1940, Britain faced a serious threat of invasion. Many destroyers were held in the Channel, ready to repel a German invasion. They suffered heavily under air attack by the ''Luftwaffe'' ''
Fliegerführer Atlantik
''Fliegerführer Atlantik'' (German: "Flyer Command Atlantic") was a World War II ''Luftwaffe'' naval air command dedicated to anti-maritime transport, anti-submarine, anti-surface enemy fleet, close air support Kriegsmarine for operations in the ...
''. Seven destroyers were lost in the Norwegian campaign, another six in the
Battle of Dunkirk
The Battle of Dunkirk (french: Bataille de Dunkerque, link=no) was fought around the French port of Dunkirk (Dunkerque) during the Second World War, between the Allies and Nazi Germany. As the Allies were losing the Battle of France on ...
and a further 10 in the Channel and North Sea between May and July, many to air attack because they lacked an adequate anti-aircraft armament. Dozens of others were damaged.
![Lorient submarine base 2007 2](https://upload.wikimedia.org/wikipedia/commons/5/50/Lorient_submarine_base_2007_2.jpg)
The completion of Hitler's campaign in Western Europe meant U-boats withdrawn from the Atlantic for the Norwegian campaign now returned to the war on trade. So at the very time the number of U-boats on patrol in the Atlantic began to increase, the number of escorts available for the convoys was greatly reduced. The only consolation for the British was that the large merchant fleets of occupied countries like Norway and the Netherlands came under British control. After the German occupation of Denmark and Norway, Britain
occupied Iceland and the
Faroe Islands
The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic island group and an autonomous territory of the Kingdom of Denmark.
They are located north-northwest of Scotland, and about halfway bet ...
, establishing bases there and preventing a German takeover.
It was in these circumstances that Winston Churchill, who had become
Prime Minister
A prime minister, premier or chief of cabinet is the head of the cabinet and the leader of the ministers in the executive branch of government, often in a parliamentary or semi-presidential system. Under those systems, a prime minister is not ...
on 10 May 1940, first wrote to
President
President most commonly refers to:
*President (corporate title)
*President (education), a leader of a college or university
*President (government title)
President may also refer to:
Automobiles
* Nissan President, a 1966–2010 Japanese ful ...
Franklin Roosevelt
Franklin Delano Roosevelt (; ; January 30, 1882April 12, 1945), often referred to by his initials FDR, was an American politician and attorney who served as the 32nd president of the United States from 1933 until his death in 1945. As the ...
to request the loan of fifty obsolescent US Navy destroyers. This eventually led to the "
Destroyers for Bases Agreement
The destroyers-for-bases deal was an agreement between the United States and the United Kingdom on September 2, 1940, according to which 50 , , and US Navy destroyers were transferred to the Royal Navy from the US Navy in exchange for land rights ...
" (effectively a sale but portrayed as a loan for political reasons), which operated in exchange for 99-year leases on certain British bases in
Newfoundland
Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...
,
Bermuda
)
, anthem = "God Save the King"
, song_type = National song
, song = " Hail to Bermuda"
, image_map =
, map_caption =
, image_map2 =
, mapsize2 =
, map_caption2 =
, subdivision_type = Sovereign state
, subdivision_name =
, e ...
and the
West Indies
The West Indies is a subregion of North America, surrounded by the North Atlantic Ocean and the Caribbean Sea that includes 13 independent island countries and 18 dependencies and other territories in three major archipelagos: the Greater A ...
, a financially advantageous bargain for the United States but militarily beneficial for Britain, since it effectively freed up British military assets to return to Europe. A significant percentage of the US population opposed entering the war, and some American politicians (including the US Ambassador to Britain,
Joseph P. Kennedy
Joseph Patrick Kennedy (September 6, 1888 – November 18, 1969) was an American businessman, investor, and politician. He is known for his own political prominence as well as that of his children and was the patriarch of the Irish-American Ken ...
) believed that Britain and its allies might actually lose. The first of these destroyers were only taken over by their British and Canadian crews in September, and all needed to be rearmed and fitted with ASDIC. It was to be many months before these ships contributed to the campaign.
'The Happy Time' (June 1940 – February 1941)
![Torpedoed merchant ship](https://upload.wikimedia.org/wikipedia/commons/4/45/Torpedoed_merchant_ship.jpg)
The early U-boat operations from the French bases were spectacularly successful. This was the heyday of the great U-boat aces like Günther Prien of ''U-47'',
Otto Kretschmer
Otto Kretschmer (1 May 1912 – 5 August 1998) was a German naval officer and submariner in World War II and the Cold War.
From September 1939 until his capture in March 1941 he sank 44 ships, including one warship, a total of 274,333 tons. For ...
(),
Joachim Schepke
Joachim Schepke (8 March 1912 – 17 March 1941) was a German U-boat commander during World War II. He was the seventh recipient of the Knight's Cross of the Iron Cross with Oak Leaves.
Schepke is credited with having sunk 36 Allied ships. Durin ...
(),
Engelbert Endrass
Engelbert Endrass (german: Engelbert Endraß) (2 March 1911 – 21 December 1941) was a German U-boat commander in World War II. He commanded the and the , being credited with sinking 22 ships on ten patrols, for a total of of Allied shipping, ...
(),
Victor Oehrn () and
Heinrich Bleichrodt
Heinrich Bleichrodt (21 October 1909 – 9 January 1977) was a German U-boat commander during the Second World War. From October 1939 until retiring from front line service in December 1943, he was credited with sinking 25 ships for a total of . ...
(). U-boat crews became heroes in Germany. From June until October 1940, over 270 Allied ships were sunk: this period was referred to by U-boat crews as "the Happy Time" ("''Die Glückliche Zeit''"). Churchill would later write: "...the only thing that ever frightened me during the war was the U-boat peril".
The biggest challenge for the U-boats was to find the convoys in the vastness of the ocean. The Germans had a handful of very long-range
Focke-Wulf Fw 200 Condor
The Focke-Wulf Fw 200 ''Condor'', also known as ''Kurier'' to the Allies (English: Courier), was a German all-metal four-engined monoplane originally developed by Focke-Wulf as a long-range airliner. A Japanese request for a long-range maritime p ...
aircraft based at
Bordeaux
Bordeaux ( , ; Gascon oc, Bordèu ; eu, Bordele; it, Bordò; es, Burdeos) is a port city on the river Garonne in the Gironde department, Southwestern France. It is the capital of the Nouvelle-Aquitaine region, as well as the prefectur ...
and
Stavanger
Stavanger (, , American English, US usually , ) is a city and municipalities of Norway, municipality in Norway. It is the fourth largest city and third largest metropolitan area in Norway (through conurbation with neighboring Sandnes) and the a ...
, which were used for reconnaissance. The Condor was a converted civilian airliner—a stop-gap solution for ''Fliegerführer Atlantik''. Due to ongoing friction between the ''Luftwaffe'' and ''Kriegsmarine'', the primary source of convoy sightings was the U-boats themselves. Since a submarine's bridge was very close to the water, their range of visual detection was quite limited.
The best source proved to be the codebreakers of ''
B-Dienst
The ''B-Dienst'' (german: Beobachtungsdienst, observation service), also called x''B-Dienst'', X-''B-Dienst'' and χ''B-Dienst'', was a Department of the German Naval Intelligence Service (german: Marinenachrichtendienst, MND III) of the OKM, t ...
'' who had succeeded in deciphering the British Naval Cypher No. 3, allowing the Germans to estimate where and when convoys could be expected.
In response, the British applied the techniques of
operations research
Operations research ( en-GB, operational research) (U.S. Air Force Specialty Code: Operations Analysis), often shortened to the initialism OR, is a discipline that deals with the development and application of analytical methods to improve deci ...
to the problem and came up with some counter-intuitive solutions for protecting convoys. They realised that the area of a convoy increased by the square of its perimeter, meaning the same number of ships, using the same number of escorts, was better protected in one convoy than in two. A large convoy was as difficult to locate as a small one. Moreover, reduced frequency also reduced the chances of detection, as fewer large convoys could carry the same amount of cargo, while large convoys take longer to assemble. Therefore, a few large convoys with apparently few escorts were safer than many small convoys with a higher ratio of escorts to merchantmen.
Instead of attacking the Allied convoys singly, U-boats were directed to work in wolf packs (''Rudel'') coordinated by radio. The boats spread out into a long patrol line that bisected the path of the Allied convoy routes. Once in position, the crew studied the horizon through
binoculars
Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...
looking for masts or smoke, or used hydrophones to pick up propeller noises. When one boat sighted a convoy, it would report the sighting to
U-boat headquarters, shadowing and continuing to report as needed until other boats arrived, typically at night. Instead of being faced by single submarines, the convoy escorts then had to cope with groups of up to half a dozen U-boats attacking simultaneously. The most daring commanders, such as Kretschmer, penetrated the escort screen and attacked from within the columns of merchantmen. The escort vessels, which were too few in number and often lacking in endurance, had no answer to multiple submarines attacking on the surface at night as their ASDIC only worked well against underwater targets. Early British marine radar, working in the
metric bands, lacked target discrimination and range. Moreover, corvettes were too slow to catch a surfaced U-boat.
Pack tactics were first used successfully in September and October 1940 to devastating effect, in a series of convoy battles. On September 21,
convoy HX 72
HX 72 was a North Atlantic convoy of the HX convoys, HX series which ran during the battle of the Atlantic in World War II. The convoy comprised 43 ships of which 11 were sunk and another damaged by German U-boats who suffered no losses.
Backg ...
of 42 merchantmen was attacked by a pack of four U-boats, which sank eleven ships and damaged two over the course of two nights. In October, the slow
convoy SC 7
SC 7 was the code name for a large Allied World War II convoy of 35 merchant ships and six escorts, which sailed eastbound from Sydney, Nova Scotia, for Liverpool and other United Kingdom ports on 5 October 1940. While crossing the Atlantic, ...
, with an escort of two
sloops
A sloop is a sailboat with a single mast typically having only one headsail in front of the mast and one mainsail aft of (behind) the mast. Such an arrangement is called a fore-and-aft rig, and can be rigged as a Bermuda rig with triangular sa ...
and two corvettes, was overwhelmed, losing 59% of its ships. The battle for
HX 79 in the following days was in many ways worse for the escorts than for SC 7. The loss of a quarter of the convoy without any loss to the U-boats, despite a very strong escort (two destroyers, four corvettes, three trawlers, and a minesweeper) demonstrated the effectiveness of the German tactics against the inadequate British anti-submarine methods. On 1 December, seven German and three Italian submarines caught
HX 90, sinking 10 ships and damaging three others. The success of pack tactics against these convoys encouraged Admiral Dönitz to adopt the wolf pack as his primary tactic.
At the end of the year 1940, the Admiralty viewed the number of ships sunk with growing alarm. Damaged ships might survive but could be out of commission for long periods. Two million gross tons of merchant shipping—13 % percent of the fleet available to the British—were under repair and unavailable, which had the same effect in slowing down cross-Atlantic supplies.
Nor were the U-boats the only threat. Following some early experience in support of the war at sea during Operation Weserübung, the ''Luftwaffe'' began to take a toll of merchant ships.
Martin Harlinghausen
Martin Harlinghausen (17 January 1902 – 22 March 1986) was a German military aviator and general. Harlinghausen specialised in maritime interdiction and anti-warship operations. During World War II Harlinghausen was the leading exponent of an ...
and his recently established command—''Fliegerführer Atlantik''—contributed small numbers of aircraft to the Battle of the Atlantic from 1941 onwards. These were primarily Fw 200 Condors and (later)
Junkers Ju 290
The Junkers Ju 290 was a large German, four-engine long-range transport, heavy bomber and maritime patrol aircraft used by the Luftwaffe late in World War II that had been developed from an earlier airliner.
Design and development
The Junkers ...
s, used for long-range reconnaissance. The Condors also bombed convoys that were beyond land-based fighter cover and thus defenceless. Initially, the Condors were very successful, claiming 365,000 tons of shipping in early 1941. These aircraft were few in number, however, and directly under ''Luftwaffe'' control; in addition, the pilots had little specialised training for anti-shipping warfare, limiting their effectiveness.
Italian submarines in the Atlantic
The Germans received help from their allies. From August 1940, a flotilla of 27 Italian submarines operated from the
BETASOM
BETASOM (an Italian language acronym of ''Bordeaux Sommergibile'' or ''Sommergibili'') was a submarine base established at Bordeaux, France by the Italian '' Regia Marina Italiana'' during World War II. From this base, Italian submarines particip ...
base in Bordeaux to attack Allied shipping in the Atlantic, initially under the command of Rear Admiral
Angelo Parona
Angelo Parona (23 April 1889 – 14 May 1977) was an Italian admiral during World War II.
Early life and career
Parona was born in Novara, Piedmont, on 23 April 1889, son of Emilio Parona and Elena Tarella. He entered the Naval Academy in Liv ...
, then of Rear Admiral
Romolo Polacchini
Romolo Polacchini (May 20, 1897 – October 16, 1968) was an Italian admiral during World War II.
Early life and career
Romolo Polacchini was born in La Spezia in 1897 and attended the Italian Naval Academy in Livorno from November 6, 1911 ...
and finally of Ship-of-the-Line Captain
Enzo Grossi __NOTOC__
Enzo Grossi (São Paulo, Brazil, 20 April 1908 - Corato, 11 August 1960); was an officer in the Regia Marina (Italian Navy) during World War II.
Life and the ''Barbarigo'' affair
During World War II he commanded the submarines ''Medusa'' ...
. The Italian submarines had been designed to operate in a different way than U-boats, and they had a number of flaws that needed to be corrected (for example huge conning towers, slow speed when surfaced, lack of modern torpedo fire control), which meant that they were ill-suited for convoy attacks, and performed better when hunting down isolated merchantmen on distant seas, taking advantage of their superior range and living standards. While initial operation met with little success (only 65343 GRT sunk between August and December 1940), the situation improved gradually over time, and up to August 1943 the 32 Italian submarines that operated there sank 109 ships of 593,864 tons, for 17 subs lost in return, giving them a subs-lost-to-tonnage sunk ratio similar to Germany's in the same period, and higher overall.
The Italians were also successful with their use of "
human torpedo
Human torpedoes or manned torpedoes are a type of diver propulsion vehicle on which the diver rides, generally in a seated position behind a fairing. They were used as secret naval weapons in World War II. The basic concept is still in use.
...
" chariots, disabling several British ships in Gibraltar.
Despite these successes, the Italian intervention was not favourably regarded by Dönitz, who characterised Italians as "inadequately disciplined" and "unable to remain calm in the face of the enemy". They were unable to co-operate in wolf pack tactics or even reliably report contacts or weather conditions, and their area of operation was moved away from those of the Germans.
Amongst the more successful Italian submarine commanders who operated in the Atlantic were
Carlo Fecia di Cossato
Carlo Fecia di Cossato (25 September 1908 – 27 August 1944) was an officer in the Regia Marina (Italian Royal Navy), in command of submarines and torpedo boats during World War II. He was credited with the confirmed sinking of 23 enemy ships (16 ...
, commander of the submarine , and
Gianfranco Gazzana-Priaroggia
Gianfranco Gazzana Priaroggia (30 August 1912 – 23 May 1943) was an officer in the Italian Royal Navy (''Regia Marina''), and was the highest-scoring Italian submarine captain of World War II.
World War II
During the war, Gazzana-Priaroggia ser ...
, commander of and then of .
ASDIC
ASDIC (also known as
SONAR
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect o ...
) was a central feature of the Battle of the Atlantic. One crucial development was the integration of ASDIC with a plotting table and weapons (
depth charge
A depth charge is an anti-submarine warfare (ASW) weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive Shock factor, hydraulic shock. Most depth ...
s and later
Hedgehog
A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are seventeen species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introducti ...
) to make an anti-submarine warfare system.
ASDIC produced an accurate range and bearing to the target, but could be fooled by
thermocline
A thermocline (also known as the thermal layer or the metalimnion in lakes) is a thin but distinct layer in a large body of fluid (e.g. water, as in an ocean or lake; or air, e.g. an atmosphere) in which temperature changes more drastically with ...
s, currents or
eddies
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid beh ...
, and schools of fish, so it needed experienced operators to be effective. ASDIC was effective only at low speeds. Above or so, the noise of the ship going through the water drowned out the echoes.
The early wartime Royal Navy procedure was to sweep the ASDIC in an arc from one side of the escort's course to the other, stopping the transducer every few degrees to send out a signal. Several ships searching together would be used in a line, apart. If an echo was detected, and if the operator identified it as a submarine, the escort would be pointed towards the target and would close at a moderate speed; the submarine's range and bearing would be plotted over time to determine course and speed as the attacker closed to within . Once it was decided to attack, the escort would increase speed, using the target's course and speed data to adjust her own course. The intention was to pass over the submarine, rolling depth charges from chutes at the stern at even intervals, while throwers fired further charges some to either side. The intention was to lay a 'pattern' like an elongated diamond, hopefully with the submarine somewhere inside it. To effectively disable a submarine, a depth charge had to explode within about . Since early ASDIC equipment was poor at determining depth, it was usual to vary the depth settings on part of the pattern.
There were disadvantages to the early versions of this system. Exercises in anti-submarine warfare had been restricted to one or two destroyers hunting a single submarine whose starting position was known, and working in daylight and calm weather. U-boats could dive far deeper than British or American submarines (over ), well below the maximum depth charge setting of British depth charges. More importantly, early ASDIC sets could not look directly down, so the operator lost contact on the U-boat during the final stages of the attack, a time when the submarine would certainly be manoeuvring rapidly. The explosion of a depth charge also disturbed the water, so ASDIC contact was very difficult to regain if the first attack had failed. It enabled the U-boat to change position with impunity.
The belief that ASDIC had solved the submarine problem, the acute budgetary pressures of the
Great Depression
The Great Depression (19291939) was an economic shock that impacted most countries across the world. It was a period of economic depression that became evident after a major fall in stock prices in the United States. The economic contagio ...
, and the pressing demands for many other types of rearmament meant little was spent on anti-submarine ships or weapons. Most British naval spending, and many of the best officers, went into the battlefleet. Critically, the British expected, as in the First World War, German submarines would be coastal craft and only threaten harbour approaches. As a result, the Royal Navy entered the
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
in 1939 without enough long-range escorts to protect ocean-going shipping, and there were no officers with experience of long-range anti-submarine warfare. The situation in
Royal Air Force
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
Coastal Command
RAF Coastal Command was a formation within the Royal Air Force (RAF). It was founded in 1936, when the RAF was restructured into Fighter, Bomber and Coastal Commands and played an important role during the Second World War. Maritime Aviation ...
was even more dire: patrol aircraft lacked the range to cover the North Atlantic and could typically only machine-gun the spot where they saw a submarine dive.
Great surface raiders
![HOOD023](https://upload.wikimedia.org/wikipedia/commons/e/e9/HOOD023.jpg)
Despite their success, U-boats were still not recognised as the foremost threat to the North Atlantic convoys. With the exception of men like Dönitz, most naval officers on both sides regarded surface warships as the ultimate commerce destroyers.
For the first half of 1940, there were no German surface raiders in the Atlantic because the German Fleet had been concentrated for the invasion of Norway. The sole pocket battleship raider, ''Admiral Graf Spee'', had been stopped at the Battle of the River Plate by an inferior and outgunned British squadron. From the summer of 1940 a small but steady stream of warships and
armed merchant raiders set sail from Germany for the Atlantic.
The power of a raider against a convoy was demonstrated by the fate of
convoy HX 84
Convoy HX 84 was the 84th of the numbered series of Allied North Atlantic HX convoys of merchant ships from Halifax, Nova Scotia, to Liverpool, England, during the Battle of the Atlantic. Thirty-eight ships escorted by the armed merchant cruise ...
, attacked by the pocket battleship on 5 November 1940. ''Admiral Scheer'' quickly sank five ships and damaged several others as the convoy scattered. Only the sacrifice of the escorting armed merchant cruiser (whose commander,
Edward Fegen
Captain Edward Stephen Fogarty Fegen, (8 October 1891 – 5 November 1940) was a Royal Navy officer and a recipient of the Victoria Cross, the highest award for gallantry in the face of the enemy that can be awarded to British and Commonwealth o ...
, was awarded a posthumous
Victoria Cross
The Victoria Cross (VC) is the highest and most prestigious award of the British honours system. It is awarded for valour "in the presence of the enemy" to members of the British Armed Forces and may be awarded posthumously. It was previously ...
) and failing light allowed the other merchantmen to escape. The British now suspended North Atlantic convoys and the
Home Fleet
The Home Fleet was a fleet of the Royal Navy that operated from the United Kingdom's territorial waters from 1902 with intervals until 1967. In 1967, it was merged with the Mediterranean Fleet creating the new Western Fleet.
Before the First ...
put to sea to try to intercept ''Admiral Scheer''. The search failed and ''Admiral Scheer'' disappeared into the South Atlantic. She reappeared in the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
the following month.
Other German surface raiders now began to make their presence felt. On Christmas Day 1940, the cruiser attacked the troop convoy WS 5A, but was driven off by the escorting cruisers. ''Admiral Hipper'' had more success two months later, on 12 February 1941, when she found the unescorted
convoy SLS 64
A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support and can help maintain cohesion within a unit. It may also be used ...
of 19 ships and sank seven of them. In January 1941, the formidable (and fast) battleships and , which outgunned any Allied ship that could catch them, put to sea from Germany to raid the shipping lanes in
Operation Berlin. With so many German raiders at large in the Atlantic, the British were forced to provide battleship escorts to as many convoys as possible. This twice saved convoys from slaughter by the German battleships. In February, the old battleship deterred an attack on
HX 106. A month later,
SL 67 was saved by the presence of .
In May, the Germans mounted the most ambitious raid of all:
Operation Rheinübung
Operation Rheinübung ("Exercise Rhine") was the sortie into the Atlantic by the new German battleship and heavy cruiser on 18–27 May 1941, during World War II. This operation to block Allies of World War II, Allied shipping to the United ...
. The new battleship and the cruiser put to sea to attack convoys. A British fleet intercepted the raiders off Iceland. In the
Battle of the Denmark Strait
The Battle of the Denmark Strait was a naval engagement in the Second World War, which took place on 24 May 1941 between ships of the Royal Navy and the ''Kriegsmarine''. The British battleship and the battlecruiser fought the German battlesh ...
, the battlecruiser was blown up and sunk, but ''Bismarck'' was damaged and had to run to France. ''Bismarck'' nearly reached her destination, but was disabled by an airstrike from the carrier ''Ark Royal'', and then sunk by the Home Fleet the next day. Her sinking marked the end of the warship raids. The advent of long-range search aircraft, notably the unglamorous but versatile
PBY Catalina
The Consolidated PBY Catalina is a flying boat and amphibious aircraft that was produced in the 1930s and 1940s. In Canadian service it was known as the Canso. It was one of the most widely used seaplanes of World War II. Catalinas served wit ...
, largely neutralised surface raiders.
In February 1942, ''Scharnhorst'', ''Gneisenau'' and ''Prinz Eugen'' moved from Brest back to Germany in the "
Channel Dash
The Channel Dash (german: Unternehmen Zerberus, Operation Cerberus) was a German naval operation during the Second World War. (Cerberus), a three-headed dog of Greek mythology who guards the gate to Hades. A (German Navy) squadron comprising ...
". While this was an embarrassment for the British, it was the end of the German surface threat in the Atlantic. The loss of ''Bismarck'', the destruction of the network of supply ships that supported surface raiders, the repeated damage to the three ships by air raids, the entry of the United States into the war,
Arctic convoys
The Arctic convoys of World War II were oceangoing convoys which sailed from the United Kingdom, Iceland, and North America to northern ports in the Soviet Union – primarily Arkhangelsk (Archangel) and Murmansk in Russia. There were 78 convoys ...
, and the perceived invasion threat to Norway had persuaded Hitler and the naval staff to withdraw.
War had come too early for the German naval expansion project
Plan Z
Plan Z was the name given to the planned re-equipment and expansion of the ''Kriegsmarine'' (German navy) ordered by Adolf Hitler in early 1939. The fleet was meant to challenge the naval power of the United Kingdom, and was to be completed by 194 ...
. Battleships powerful enough to destroy any convoy escort, with escorts able to annihilate the convoy, were never achieved. Although the number of ships the raiders sank was relatively small compared with the losses to U-boats, mines, and aircraft, their raids severely disrupted the Allied convoy system, reduced British imports, and strained the Home Fleet.
Escort groups (March–May 1941)
![The battle of the Atlantic 1941 map](https://upload.wikimedia.org/wikipedia/commons/e/ec/The_battle_of_the_Atlantic_1941_map.svg)
The disastrous convoy battles of October 1940 forced a change in British tactics. The most important of these was the introduction of permanent escort groups to improve the co-ordination and effectiveness of ships and men in battle. British efforts were helped by a gradual increase in the number of escort vessels available as the old
ex-American destroyers and the new British- and Canadian-built s were now coming into service in numbers. Many of these ships became part of the huge expansion of the Royal Canadian Navy, which grew from a handful of destroyers at the outbreak of war to take an increasing share of convoy escort duty. Others of the new ships were crewed by Free French, Norwegian and Dutch, but these were a tiny minority of the total number, and directly under British command. By 1941 American public opinion had begun to swing against Germany, but the war was still essentially Great Britain and the Empire against Germany.
Initially, the new escort groups consisted of two or three destroyers and half a dozen corvettes. Since two or three of the group would usually be in dock repairing weather or battle damage, the groups typically sailed with about six ships. The training of the escorts also improved as the realities of the battle became obvious. A new base was set up at
Tobermory in the
Hebrides
The Hebrides (; gd, Innse Gall, ; non, Suðreyjar, "southern isles") are an archipelago off the west coast of the Scottish mainland. The islands fall into two main groups, based on their proximity to the mainland: the Inner and Outer Hebrid ...
to prepare the new escort ships and their crews for the demands of battle under the strict regime of Vice-Admiral
Gilbert O. Stephenson.
In February 1941, the Admiralty moved the headquarters of Western Approaches Command from
Plymouth
Plymouth () is a port city and unitary authority in South West England. It is located on the south coast of Devon, approximately south-west of Exeter and south-west of London. It is bordered by Cornwall to the west and south-west.
Plymouth ...
to
Liverpool
Liverpool is a city and metropolitan borough in Merseyside, England. With a population of in 2019, it is the 10th largest English district by population and its metropolitan area is the fifth largest in the United Kingdom, with a popul ...
, where much closer contact with, and control of, the Atlantic convoys was possible. Greater co-operation with supporting aircraft was also achieved. In April, the Admiralty took over operational control of Coastal Command aircraft. At a tactical level, new short-wave radar sets that could detect surfaced U-boats and were suitable for both small ships and aircraft began to arrive during 1941.
The impact of these changes first began to be felt in the battles during the spring of 1941. In early March, Prien in ''U-47'' failed to return from patrol. Two weeks later, in the battle of
Convoy HX 112
HX 112 was a North Atlantic convoy of the HX series which ran during the battle of the Atlantic in the Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 19 ...
, the newly formed 3rd Escort Group of four destroyers and two corvettes held off the U-boat pack. ''U-100'' was detected by the primitive radar on the destroyer , rammed and sunk. Shortly afterwards ''U-99'' was also caught and sunk, its crew captured. Dönitz had lost his three leading aces: Kretschmer, Prien, and Schepke.
Dönitz now moved his wolf packs further west, in order to catch the convoys before the anti-submarine escort joined. This new strategy was rewarded at the beginning of April when the pack found
Convoy SC 26
SC 26 was a North Atlantic convoy of the SC series which ran during the battle of the Atlantic in World War II.
Prelude
SC 26 was an east-bound convoy of 23 ships which sailed from Halifax on 20 March 1941 bound for Liverpool. It carried war m ...
before its anti-submarine escort had joined. Ten ships were sunk, but another U-boat was lost.
The field of battle widens (June–December 1941)
Growing American activity
![Convoy WS-12 en route to Cape Town, 1941](https://upload.wikimedia.org/wikipedia/commons/6/6a/Convoy_WS-12_en_route_to_Cape_Town%2C_1941.jpg)
In June 1941, the British decided to provide convoy escort for the full length of the North Atlantic crossing. To this end, the Admiralty asked the Royal Canadian Navy on May 23, to assume the responsibility for protecting convoys in the western zone and to establish the base for its escort force at
St. John's, Newfoundland. On June 13, 1941, Commodore
Leonard Murray, Royal Canadian Navy, assumed his post as Commodore Commanding
Newfoundland Escort Force
The Newfoundland Escort Force (NEF) was a Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's count ...
, under the overall authority of the Commander-in-Chief, Western Approaches, at Liverpool. Six Canadian destroyers and 17 corvettes, reinforced by seven destroyers, three sloops, and five corvettes of the Royal Navy, were assembled for duty in the force, which escorted the convoys from Canadian ports to Newfoundland and then on to a meeting point south of Iceland, where the British escort groups took over.
By 1941, the United States was taking an increasing part in the war, despite its nominal neutrality. In April 1941 President Roosevelt extended the
Pan-American Security Zone
During the early years of World War II before the United States became a formal belligerent, President Franklin D. Roosevelt declared a region of the Atlantic, adjacent to the Americas as the Pan-American Security Zone. Within this zone, United Sta ...
east almost as far as
Iceland
Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...
. British forces occupied Iceland when Denmark fell to the Germans in 1940; the US was persuaded to provide forces to relieve British troops on the island. American warships began escorting Allied convoys in the western Atlantic as far as Iceland, and had several hostile encounters with U-boats.
In June 1941, the US realised the tropical Atlantic had become dangerous for unescorted American as well as British ships. On May 21, , an American vessel carrying no military supplies, was stopped by west of
Freetown, Sierra Leone
Freetown is the capital and largest city of Sierra Leone. It is a major port city on the Atlantic Ocean and is located in the Western Area of the country. Freetown is Sierra Leone's major urban, economic, financial, cultural, educational and po ...
. After its passengers and crew were allowed thirty minutes to board lifeboats, ''U-69'' torpedoed, shelled, and sank the ship. The survivors then drifted without rescue or detection for up to eighteen days. When news of the sinking reached the US, few shipping companies felt truly safe anywhere. As ''Time'' magazine noted in June 1941, "if such sinkings continue, U.S. ships bound for other places remote from fighting fronts, will be in danger. Henceforth the U.S. would either have to recall its ships from the ocean or enforce its right to the free use of the seas."
A
Mid-Ocean Escort Force
Mid-Ocean Escort Force (MOEF) referred to the organisation of anti-submarine escorts for World War II trade convoys between Canada and Newfoundland, and the British Isles. The allocation of United States, British, and Canadian escorts to these co ...
of British, and Canadian, and American destroyers and corvettes was organised following the declaration of war by the United States in December 1941.
At the same time, the British were working on a number of technical developments which would address the German submarine superiority. Though these were British inventions, the critical technologies were provided freely to the US, which then renamed and manufactured them. Likewise, the US provided the British with
Catalina
Catalina may refer to:
Arts and media
* ''The Catalina'', a 2012 American reality television show
* ''Catalina'' (novel), a 1948 novel by W. Somerset Maugham
* Catalina (''My Name Is Earl''), character from the NBC sitcom ''My Name Is Earl''
...
flying boats and
Liberator bombers that were important contributions to the war effort.
Catapult aircraft merchantmen
![The Royal Navy during the Second World War A9421](https://upload.wikimedia.org/wikipedia/commons/2/22/The_Royal_Navy_during_the_Second_World_War_A9421.jpg)
Aircraft ranges were constantly improving, but the Atlantic was far too large to be covered completely by land-based types. A stop-gap measure was instituted by fitting ramps to the front of some of the cargo ships known as ''catapult aircraft merchantmen'' (
CAM ships), equipped with a lone expendable
Hurricane
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
fighter aircraft. When a German bomber approached, the fighter was launched off the end of the ramp
with a large rocket to shoot down or drive off the German aircraft, the pilot then
ditching
In aviation, a water landing is, in the broadest sense, an Landing, aircraft landing on a body of water. Seaplanes, such as floatplanes and flying boats, land on water as a normal operation. Ditching is a controlled emergency landing on the ...
in the water and – in the best case – recovered by ship. Nine combat launches were made, resulting in the destruction of eight Axis aircraft for the loss of one Allied pilot.
Although CAM ships and their Hurricanes did not down a great number of enemy aircraft, such aircraft were mostly
Fw 200 Condors that would often shadow the convoy out of range of the convoy's guns, reporting back the convoy's course and position so that U-boats could then be directed on to the convoy. The CAM ships and their Hurricanes thus justified the cost in fewer ship losses overall.
High-frequency direction-finding
![HMS Kite IWM FL 22973](https://upload.wikimedia.org/wikipedia/commons/3/31/HMS_Kite_IWM_FL_22973.jpg)
One of the more important developments was ship-borne direction-finding radio equipment, known as HF/DF (high-frequency direction-finding, or
Huff-Duff
High-frequency direction finding, usually known by its abbreviation HF/DF or nickname huff-duff, is a type of radio direction finder (RDF) introduced in World War II. High frequency (HF) refers to a radio band that can effectively communicate over ...
), which started to be fitted to escorts from February 1942. These sets were common items of equipment by the spring of 1943.
HF/DF let an operator determine the direction of a radio signal, regardless of whether the content could be read. Since the wolf pack relied on U-boats reporting convoy positions by radio, there was a steady stream of messages to intercept. An escort could then run in the direction of the signal and attack the U-boat, or at least force it to submerge (causing it to lose contact), which might prevent an attack on the convoy. When two ships fitted with HF/DF accompanied a convoy, a fix on the transmitter's position, not just direction, could be determined. However, the standard approach of anti-submarine warships was immediately to "run-down" the bearing of a detected signal, hoping to spot the U-boat on the surface and make an immediate attack. Range could be estimated by an experienced operator from the signal strength. Usually the target was found visually. If the submarine was slow to dive, the guns were used; otherwise an ASDIC (Sonar) search was started where the swirl of water of a crash-diving submarine was observed. In good visibility a U-boat might try and outrun an escort on the surface whilst out of gun range. Running down the bearing of a HF/DF signal was also used by
escort carrier
The escort carrier or escort aircraft carrier (U.S. hull classification symbol CVE), also called a "jeep carrier" or "baby flattop" in the United States Navy (USN) or "Woolworth Carrier" by the Royal Navy, was a small and slow type of aircraft ...
s (particularly , operating south of the Azores), sending aircraft along the line of the bearing to force the submarine to submerge by strafing and then attack with depth charges or a
FIDO homing torpedo.
The British also made extensive use of shore HF/DF stations, to keep convoys updated with positions of U-boats.
The radio technology behind direction finding was simple and well understood by both sides, but the technology commonly used before the war used a manually-rotated aerial to fix the direction of the transmitter. This was delicate work, took quite a time to accomplish to any degree of accuracy, and since it only revealed the line along which the transmission originated a single set could not determine if the transmission was from the true direction or its reciprocal 180 degrees in the opposite direction. Two sets were required to fix the position. Believing this to still be the case, German U-boat radio operators considered themselves fairly safe if they kept messages short. The British, however, developed an oscilloscope-based indicator which instantly fixed the direction and its reciprocal the moment a radio operator touched his
Morse
Morse may refer to:
People
* Morse (surname)
* Morse Goodman (1917-1993), Anglican Bishop of Calgary, Canada
* Morse Robb (1902–1992), Canadian inventor and entrepreneur
Geography Antarctica
* Cape Morse, Wilkes Land
* Mount Morse, Churchi ...
key. It worked simply with a crossed pair of conventional and fixed directional aerials, the oscilloscope display showing the relative received strength from each aerial as an elongated ellipse showing the line relative to the ship. The innovation was a 'sense' aerial, which, when switched in, suppressed the ellipse in the 'wrong' direction leaving only the correct bearing. With this there was hardly any need to triangulate—the escort could just run down the precise bearing provided, estimating range from the signal strength, and use either efficient look-outs or radar for final positioning. Many U-boat attacks were suppressed and submarines sunk in this way—a good example of the great difference apparently minor aspects of technology could make to the battle.
Enigma cipher
The way Dönitz conducted the U-boat campaign required relatively large volumes of radio traffic between U-boats and headquarters. This was thought to be safe as the radio messages were encrypted using the
Enigma
Enigma may refer to:
*Riddle, someone or something that is mysterious or puzzling
Biology
*ENIGMA, a class of gene in the LIM domain
Computing and technology
* Enigma (company), a New York-based data-technology startup
* Enigma machine, a family ...
cipher machine
In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode i ...
, which the Germans considered unbreakable. In addition, the ''Kriegsmarine'' used much more secure operating procedures than the ''Heer'' (Army) or ''Luftwaffe'' (Air Force). The machine's three rotors were chosen from a set of eight (rather than the other services' five). The rotors were changed every other day using a system of
key
Key or The Key may refer to:
Common meanings
* Key (cryptography), a piece of information that controls the operation of a cryptography algorithm
* Key (lock), device used to control access to places or facilities restricted by a lock
* Key (map ...
sheets and the message settings were different for every message and determined from
"bigram tables" that were issued to operators. In 1939, it was generally believed at the British
Government Code and Cypher School (GC&CS)
Government Communications Headquarters, commonly known as GCHQ, is an intelligence agency, intelligence and security agency, security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the G ...
at
Bletchley Park
Bletchley Park is an English country house and estate in Bletchley, Milton Keynes ( Buckinghamshire) that became the principal centre of Allied code-breaking during the Second World War. The mansion was constructed during the years following ...
that naval Enigma could not be broken. Only the head of the German Naval Section,
Frank Birch
Francis Lyall "Frank" Birch, (5 December 1889 – 14 February 1956) was a British cryptographer and actor. He was educated at Eton College and King's College, Cambridge.
During World War I, he served as a lieutenant commander with the R ...
, and the mathematician
Alan Turing
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical com ...
believed otherwise.
![Enigma rotors and spindle showing contacts rachet and notch](https://upload.wikimedia.org/wikipedia/commons/d/d8/Enigma_rotors_and_spindle_showing_contacts_rachet_and_notch.jpg)
The British codebreakers needed to know the wiring of the special naval Enigma rotors, and the destruction of by in February 1940 provided this information. In early 1941, the Royal Navy made a concerted effort to assist the codebreakers, and on May 9 crew members of the destroyer boarded and recovered her cryptologic material, including bigram tables and current Enigma keys. The captured material allowed all U-boat traffic to be read for several weeks, until the keys ran out; the familiarity codebreakers gained with the usual content of messages helped in breaking new keys.
During 1940, 178 Enigma messages were broken on the British bombe.
Throughout the summer and autumn of 1941, Enigma intercepts (combined with HF/DF) enabled the British to plot the positions of U-boat patrol lines and route convoys around them. Merchant ship losses dropped by over two-thirds in July 1941, and the losses remained low until November.
During May 1943, the US Navy began using a 4-rotor bombe machines used drums for the Enigma rotors at 34 times the speed of the early British bombe machines. By September 1944, the US Navy had 121 bombes.
This Allied advantage was offset by the growing numbers of U-boats coming into service. The
Type VIIC began reaching the Atlantic in large numbers in 1941; by the end of 1945, 568 had been
commissioned. Although the Allies could protect their convoys in late 1941, they were not sinking many U-boats. The Flower-class corvette escorts could detect and defend, but they were not fast enough to attack effectively.
U-boat captured by an aircraft
An extraordinary incident occurred when a Coastal Command
Hudson
Hudson may refer to:
People
* Hudson (given name)
* Hudson (surname)
* Henry Hudson, English explorer
* Hudson (footballer, born 1986), Hudson Fernando Tobias de Carvalho, Brazilian football right-back
* Hudson (footballer, born 1988), Hudso ...
of
209 Squadron captured ''U-570'' on 27 August 1941 about south of Iceland. Squadron Leader J. Thompson sighted the U-boat on the surface, immediately dived at his target, and released four depth charges as the submarine crash dived. The U-boat surfaced again, a number of crewmen appeared on deck, and Thompson engaged them with his aircraft's guns. The crewmen returned to the conning tower while under fire. A few moments later, a white flag and a similarly coloured board were displayed. Thompson called for assistance and circled the German vessel. A Catalina from 209 Squadron took over watching the damaged U-boat until the arrival of the armed trawler ''Kingston Agate'' under Lt Henry Owen L'Estrange. The following day the U-boat was beached in an Icelandic cove. Although no codes or secret papers were recovered, the British now possessed a complete U-boat. After a refit, ''U-570'' was commissioned into the Royal Navy as .
Mediterranean diversion
In October 1941, Hitler ordered Dönitz to move U-boats into the Mediterranean to support German operations in that theatre. The resulting concentration near Gibraltar resulted in a series of battles around the Gibraltar and Sierra Leone convoys. In December 1941,
Convoy HG 76
HG 76 (19 to 23 December 1941) was an Allied convoy of the HG (Homeward from Gibraltar) series, during the Second World War. It was notable for the destruction of five German U-boats (the true total was not known to the British until after the ...
sailed, escorted by the 36th Escort Group of two sloops and six corvettes under Captain
Frederic John Walker
Captain Frederic John Walker, (3 June 1896 – 9 July 1944) (his first name is given as Frederick in the Oxford Dictionary of National Biography and some London Gazette entries) was a Royal Navy officer noted for his exploits during the Second ...
, reinforced by the first of the new
escort carrier
The escort carrier or escort aircraft carrier (U.S. hull classification symbol CVE), also called a "jeep carrier" or "baby flattop" in the United States Navy (USN) or "Woolworth Carrier" by the Royal Navy, was a small and slow type of aircraft ...
s, , and three destroyers from Gibraltar. The convoy was immediately intercepted by the waiting U-boat pack, resulting in a brutal battle. Walker was a tactical innovator, his ships' crews were highly trained and the presence of an escort carrier meant U-boats were frequently sighted and forced to dive before they could get close to the convoy. Over the next five days, five U-boats were sunk (four by Walker's group), despite the loss of ''Audacity'' after two days. The British lost ''Audacity'', a destroyer and only two merchant ships. The battle was the first clear Allied convoy victory.
Through dogged effort, the Allies slowly gained the upper hand until the end of 1941. Although Allied warships failed to sink U-boats in large numbers, most convoys evaded attack completely. Shipping losses were high, but manageable.
Operation Drumbeat (January–June 1942)
![Casablanca convoy](https://upload.wikimedia.org/wikipedia/commons/6/61/Casablanca_convoy.jpg)
The
attack on Pearl Harbor
The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, j ...
and the subsequent German declaration of war on the United States had an immediate effect on the campaign. Dönitz promptly planned to attack shipping off the
American East Coast
The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the coastline along which the Eastern United States meets the North Atlantic Ocean. The eastern seaboard contains the coa ...
. He had only 12
Type IX
The Type IX U-boat was designed by Nazi Germany's '' Kriegsmarine'' in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. Type IX boats were briefly used for patrols off the eastern Un ...
boats able to reach US waters; half of them had been diverted by Hitler to the Mediterranean. One of the remainder was under repair, leaving only five boats for
Operation Drumbeat
The "Second Happy Time" (; officially Operation Paukenschlag ("Operation Drumbeat"), and also known among German submarine commanders as the "American Shooting Season") was a phase in the Battle of the Atlantic during which Axis powers, Axis s ...
(''Paukenschlag''), sometimes called by the Germans the "Second happy time."
The US, having no direct experience of modern naval war on its own shores, did not employ a black-out. U-boats simply stood off shore at night and picked out ships silhouetted against city lights. Admiral
Ernest King
Ernest Joseph King (23 November 1878 – 25 June 1956) was an American naval officer who served as Commander in Chief, United States Fleet (COMINCH) and Chief of Naval Operations (CNO) during World War II. As COMINCH-CNO, he directed the Un ...
, Commander-in-Chief United States Fleet (Cominch), who disliked the British, initially rejected Royal Navy calls for a coastal black-out or convoy system. King has been criticised for this decision, but his defenders argue the United States destroyer fleet was limited (partly because of the sale of 50 old destroyers to Britain earlier in the war), and King claimed it was far more important that destroyers protect Allied troop transports than merchant shipping. His ships were also busy convoying
Lend-Lease
Lend-Lease, formally the Lend-Lease Act and introduced as An Act to Promote the Defense of the United States (), was a policy under which the United States supplied the United Kingdom, the Soviet Union and other Allied nations with food, oil, ...
material to the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
, as well as fighting the Japanese in the Pacific. King could not require coastal black-outs—the Army had legal authority over all civil defence—and did not follow advice the Royal Navy (or Royal Canadian Navy) provided that even unescorted convoys would be safer than merchants sailing individually. No troop transports were lost, but merchant ships sailing in US waters were left exposed and suffered accordingly. Britain eventually had to build coastal escorts and provide them to the US in a "reverse Lend Lease", since King was unable (or unwilling) to make any provision himself.
The first U-boats reached US waters on January 13, 1942. By the time they withdrew on February 6, they had sunk 156,939 tonnes of shipping without loss. The first batch of Type IXs was followed by more Type IXs and Type VIIs supported by
Type XIV "
Milk Cow" tankers which provided refuelling at sea. They sank 397 ships totalling over 2 million tons. (As mentioned previously, not a single troop transport was lost.) In 1943, the United States launched over 11 million tons of merchant shipping; that number declined in the later war years, as priorities moved elsewhere.
In May, King (by this time both Cominch and
CNO) finally scraped together enough ships to institute a convoy system. This quickly led to the loss of seven U-boats. The US did not have enough ships to cover all the gaps; the U-boats continued to operate freely during the
Battle of the Caribbean
The Battle of the Caribbean refers to a naval campaign waged during World War II that was part of the Battle of the Atlantic, from 1941 to 1945. German U-boats and Italian submarines attempted to disrupt the Allied supply of oil and other mate ...
and throughout the
Gulf of Mexico
The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
(where they effectively closed several US ports) until July, when the British-loaned escorts began arriving. These included 24 armed anti-submarine trawlers crewed by the Royal Naval Patrol Service; many had previously been peacetime fishermen. On July 3, 1942, one of these trawlers, HMS ''Le Tigre'' proved her worth by picking up 31 survivors from the American merchant ''Alexander Macomb''. Shortly after, ''Le Tigre'' managed to hunt down the U-boat that had torpedoed the merchant ship, which was then sunk by ; credit was awarded to ''Le Tigre''. The institution of an interlocking convoy system on the American coast and in the
Caribbean Sea
The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...
in mid-1942 resulted in an immediate drop in attacks in those areas. As a result of the increased coastal convoy escort system, the U-boats' attention was shifted back to the Atlantic convoys. For the Allies, the situation was serious but not critical throughout much of 1942.
Operation Drumbeat had one other effect. It was so successful that Dönitz's policy of economic war was seen, even by Hitler, as the only effective use of the U-boat; he was given complete freedom to use them as he saw fit. Meanwhile, Hitler sacked Raeder after the embarrassing
Battle of the Barents Sea
The Battle of the Barents Sea was a World War II naval engagement on 31 December 1942 between warships of the German Navy (''Kriegsmarine'') and British ships escorting convoy JW 51B to Kola Inlet in the USSR. The action took place in the Bare ...
, in which two German heavy cruisers were beaten off by half a dozen British destroyers. Dönitz was eventually made Grand Admiral, and all building priorities turned to U-boats.
Battle returns to the mid-Atlantic (July 1942 – February 1943)
With the US finally arranging convoys, ship losses to the U-boats quickly dropped, and Dönitz realised his U-boats were better used elsewhere. On July 19, 1942, he ordered the last boats to withdraw from the United States Atlantic coast; by the end of July 1942 he had shifted his attention back to the North Atlantic, where allied aircraft could not provide cover—i.e. the
Black Pit
The Mid-Atlantic gap is a geographical term applied to an undefended area beyond the reach of land-based RAF Coastal Command anti-submarine warfare, antisubmarine (A/S) aircraft during the Battle of the Atlantic in the World War II, Second World ...
.
Convoy SC 94
Convoy SC 94 was the 94th of the numbered series of World War II Slow Convoys of merchant ships from Sydney, Cape Breton Island, Nova Scotia, to Liverpool.Hague 2000 p.133 The ships departed Sydney on 31 July 1942 and were met by Mid-Ocean Es ...
marked the return of the U-boats to the convoys from Canada to Britain. The command centre for the submarines operating in the West, including the Atlantic also changed, moving to a newly constructed command bunker at the
Château de Pignerolle
The Chateau de Pignerolle is located to the east of Angers in the commune of Saint-Barthélemy-d'Anjou in the department of Maine-et-Loire in France.
Construction
Constructed in 1776 for the director of the equestrian academy in Angers, Marcel Av ...
just east of
Angers
Angers (, , ) is a city in western France, about southwest of Paris. It is the prefecture of the Maine-et-Loire department and was the capital of the province of Anjou until the French Revolution. The inhabitants of both the city and the prov ...
on the Loire river. The headquarters was commanded by
Hans-Rudolf Rösing
Hans-Rudolf Rösing (28 September 1905 – 16 December 2004) was a German U-boat commander in World War II and later served in the Bundesmarine of the Federal Republic of Germany. He was a recipient of the Knight's Cross of the Iron Cross, of Nazi ...
.
There were enough U-boats spread across the Atlantic to allow several wolf packs to attack many different convoy routes. Often as many as 10 to 15 boats would attack in one or two waves, following convoys like
SC 104 and
SC 107 by day and attacking at night. Convoy losses quickly increased and in October 1942, 56 ships of over 258,000 tonnes were sunk in the "air gap" between
Greenland
Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
and Iceland.
U-boat losses also climbed. In the first six months of 1942, 21 were lost, less than one for every 40 merchant ships sunk. In August and September, 60 were sunk, one for every 10 merchant ships, almost as many as in the previous two years.
On November 19, 1942, Admiral Noble was replaced as Commander-in-Chief of
Western Approaches Command
Commander-in-Chief, Western Approaches was the commander of a major operational command of the Royal Navy during World War II. The admiral commanding, and his forces, sometimes informally known as 'Western Approaches Command,' were responsibl ...
by Admiral
Sir Max Horton. Horton used the growing number of escorts becoming available to organise "support groups", to reinforce convoys that came under attack. Unlike the regular escort groups, support groups were not directly responsible for the safety of any particular convoy. This gave them much greater tactical flexibility, allowing them to detach ships to hunt submarines spotted by reconnaissance or picked up by HF/DF. Where regular escorts would have to break off and stay with their convoy, the support group ships could keep hunting a U-boat for many hours. One tactic introduced by
Captain John Walker was the "hold-down", where a group of ships would patrol over a submerged U-boat until its air ran out and it was forced to the surface; this might take two or three days.
Western Approaches Tactical Unit
Between February 1942 and July 1945, about 5,000 naval officers played war games at ''Western Approaches Tactical Unit''. Many game graduates believe that the battle they fought on the linoleum floor is essential to their subsequent victory at sea. In November 1942,
Admiral Horton tested ''Beta Search'' in a wargame. Janet Okell and Jean Laidlaw played the role of the escorts. Five times in a row Okell and Laidlaw sank the submarine of Admiral Horton, the commander-in chief of Western Approaches.
Ahead-throwing weapons
![Hedgehog anti-submarine mortar](https://upload.wikimedia.org/wikipedia/commons/3/33/Hedgehog_anti-submarine_mortar.jpg)
At the start of World War II, the depth charge was the only weapon available to a vessel for destroying a submerged submarine. Depth charges were dropped over the stern and thrown to the side of a warship travelling at speed. Early models of ASDIC/Sonar searched only ahead, astern and to the sides of the anti-submarine vessel that was using it: there was no downward-looking capability. So there was a time lag between the last fix obtained on the submarine and the warship reaching a point above that position. Then the depth charges had to sink to the depth at which they were set to explode. During those two delays, a capable submarine commander would manoeuvre rapidly to a different position and avoid the attack. The depth charges then left an area of disturbed water, through which it was difficult to regain ASDIC/Sonar contact. In response to this problem, one of the solutions developed by the Royal Navy was the ahead-throwing anti-submarine weapon—the first of which was Hedgehog.
Hedgehog
Hedgehog was a multiple
spigot mortar
A mortar is usually a simple, lightweight, man-portable, muzzle-loaded weapon, consisting of a smooth-bore (although some models use a rifled barrel) metal tube fixed to a base plate (to spread out the recoil) with a lightweight bipod mount and a ...
, which fired contact-fused bombs ahead of the firing ship while the target was still within the ASDIC beam. These started to be installed on anti-submarine ships from late 1942. The warship could approach slowly (as it did not have to clear the area of exploding depth charges to avoid damage) and so its position was less obvious to the submarine commander as it was making less noise. Because hedgehog only exploded if it hit the submarine, if the target was missed, there was no disturbed water to make tracking difficult—and contact had not been lost in the first place.
Squid
Squid
True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...
was an improvement on 'Hedgehog' introduced in late 1943. A three-barrelled mortar, it projected charges ahead or abeam; the charges' firing pistols were automatically set just prior to launch. The more advanced installations had Squid linked to the latest ASDIC sets so that Squid was fired automatically.
Leigh Light
![Leigh Light](https://upload.wikimedia.org/wikipedia/commons/b/b6/Leigh_Light.jpg)
Detection by radar-equipped aircraft could suppress U-boat activity over a wide area, but an aircraft attack could only be successful with good visibility. U-boats were relatively safe from aircraft at night for two reasons: 1) radar then in use could not detect them at less than ; 2) flares deployed to illuminate any attack gave adequate warning for evasive manoeuvres. The introduction of the
Leigh Light by the British in January 1942 solved the second problem, thereby becoming a significant factor in the Battle for the Atlantic. Developed by RAF officer
H. Leigh, it was a powerful and controllable searchlight mounted primarily to
Wellington bombers and B-24 Liberators. These aircraft first made contact with enemy submarines using air-to-surface-vessel (ASV) radar. Then, about a from the target, the Leigh Light would be switched on. It immediately and accurately illuminated the enemy, giving U-boat commanders less than 25 seconds to react before they were attacked with depth charges. The first confirmed kill using this technology was ''U-502'' on July 5, 1942.
The Leigh Light enabled the British to attack enemy subs on the surface at night, forcing German and Italian commanders to remain underwater especially when coming into port at sub bases in the Bay of Biscay.
U-boat commanders who survived such attacks reported a particular fear of this weapon system since aircraft could not be seen at night, and the noise of an approaching aircraft was inaudible above the din of the sub's engines. Subsequently, the common practice of surfacing at night to recharge batteries and refresh air was mostly abandoned as it was safer to perform these tasks during daylight hours when enemy planes could be spotted. A drop in Allied shipping losses from 600,000 to 200,000 tons per month was attributed to this device.
Metox receiver
![The Battle of the Atlantic 1939-1945 A22031](https://upload.wikimedia.org/wikipedia/commons/1/12/The_Battle_of_the_Atlantic_1939-1945_A22031.jpg)
By August 1942, U-boats were being fitted with radar detectors to enable them to avoid sudden ambushes by radar-equipped aircraft or ships. The first such receiver, named
Metox
The R600A Metox, named after its manufacturer, was a pioneering high-frequency radar warning receiver (RWR) manufactured by a small French company in occupied Paris. It was tuned to receive the signals used by many British radars of the early a ...
after its French manufacturer, was capable of picking up the metric radar bands used by the early radars. This not only enabled U-boats to avoid detection by Canadian escorts, which were equipped with obsolete radar sets, but allowed them to track convoys where these sets were in use.
However, it also caused problems for the Germans, as it sometimes detected stray radar emissions from distant ships or planes, causing U-boats to submerge when they were not in actual danger, preventing them from recharging batteries or using their surfaced speed.
Metox provided the U-boat commander with an advantage that had not been anticipated by the British. The Metox set beeped at the pulse rate of the hunting aircraft's radar, approximately once per second. When the radar operator came within of the U-boat, he changed the range of his radar. With the change of range, the radar doubled its pulse repetition frequency and as a result, the Metox beeping frequency also doubled, warning the commander that he had been detected.
Germans break Admiralty codes
In 1941, American intelligence informed Rear Admiral
John Henry Godfrey
Admiral John Henry Godfrey CB (10 July 1888 – 29 August 1970) was an officer of the Royal Navy and Royal Indian Navy, specialising in navigation. Ian Fleming is said to have based James Bond's boss, " M", on Godfrey.
Life and career
Godfr ...
that the UK naval codes could be broken. In March, 1942, the Germans broke Naval Cipher 3, the code for Anglo-American communication. Eighty percent of the Admiralty messages from March, 1942 to June 1943 were read by the Germans. The sinking of Allied merchant ships increased dramatically.
Günter Hessler
Günter Hessler (14 June 1909 – 4 April 1968) was a German naval officer during World War II. He commanded the Type IXB U-boat , sinking twenty-one ships on three patrols, totalling of Allied shipping. Hessler was a recipient of the Knight's ...
, Admiral Dönitz's son-in-law and first staff officer at U-boat Command, said:
"We had reached a stage when it took one or two days to decrypt the British radio messages. On occasions only a few hours were required. We could sometimes deduce when and how they would take advantage of the gaps in our U-boat dispositions. Our function was to close those gaps just before the convoys were due."
The code breakers of Bletchley Park assigned only two people to evaluate whether the Germans broke the code. After five months, they finally determined that the codes were broken. In August, 1942, the UK Admiralty was informed. However, the Admiralty did not change the codes until June, 1943.
Captain Raymond Dreyer, deputy staff signals officer at Western Approaches, the British HQ for the Battle of the Atlantic in Liverpool, said, "Some of their most successful U-boat pack attacks on our convoys were based on information obtained by breaking our ciphers."
Enigma in 1942
On February 1, 1942, the ''Kriegsmarine'' switched the U-boats to a new Enigma network (TRITON) that used the
new, four-rotor, Enigma machines. This new key could not be read by codebreakers; the Allies no longer knew where the U-boat patrol lines were. This made it far more difficult to evade contact, and the wolf packs ravaged many convoys. This state persisted for ten months. To obtain information on submarine movements the Allies had to make do with HF/DF fixes and decrypts of ''Kriegsmarine'' messages encoded on earlier Enigma machines. These messages included signals from coastal forces about U-boat arrivals and departures at their bases in France, and the reports from the U-boat training command. From these clues, Commander Rodger Winn's Admiralty Submarine Tracking Room supplied their best estimates of submarine movements, but this information was not enough.
Then on October 30, crewmen from salvaged Enigma material from as she foundered off
Port Said
Port Said ( ar, بورسعيد, Būrsaʿīd, ; grc, Πηλούσιον, Pēlousion) is a city that lies in northeast Egypt extending about along the coast of the Mediterranean Sea, north of the Suez Canal. With an approximate population of 6 ...
. This allowed the codebreakers to break TRITON, a feat credited to
Alan Turing
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical com ...
. By December 1942, Enigma decrypts were again disclosing U-boat patrol positions, and shipping losses declined dramatically once more.
German Command centre
Following the
St Nazaire Raid
The St Nazaire Raid or Operation Chariot was a British amphibious attack on the heavily defended Normandie dry dock at St Nazaire in German-occupied France during the Second World War. The operation was undertaken by the Royal Navy (RN) a ...
on 28 March 1942, Raeder decided the risk of further seaborne attack was high and relocated the western command centre for
U-boat
U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role ...
s to the Château de Pignerolle, where a command bunker was built and from where all Enigma radio messages between German command and Atlantic based operational U-boats were transmitted/received. In July 1942, Hans-Rudolf Rösing was appointed as FdU West (''
Führer der Unterseeboote West''). Pignerolle became his headquarters.
Climax of the campaign (March–May 1943, "Black May")
After
Convoy ON 154
Convoy ON 154 - also ON(S) 154 or ONS 154 - was a North Atlantic convoy of the ON series which ran during the battle of the Atlantic in World War II. It was the 154th of the numbered series of merchant ship convoys Outbound from the British ...
, winter weather provided a brief respite from the fighting in January before convoys
SC 118 and
ON 166 in February 1943, but in the spring, convoy battles started up again with the same ferocity. There were so many U-boats on patrol in the North Atlantic, it was difficult for convoys to evade detection, resulting in a succession of vicious battles.
On March 10, 1943, the Germans added a refinement to the U-boat Enigma key, which blinded the Allied codebreakers at Bletchley Park for 9 days. That month saw the battles of convoys
UGS 6,
HX 228,
SC 121
South Carolina Highway 121 (SC 121) is a major state highway that travels north and south in central parts of the U.S. state of South Carolina. The highway is actually part of a long multi-state highway that also exists in Florida and G ...
,
SC 122 and HX 229. One hundred and twenty ships were sunk worldwide, 82 ships of 476,000 tons in the Atlantic, while 12 U-boats were destroyed.
The supply situation in Britain was such that there was talk of being unable to continue the war, with supplies of fuel being particularly low. The situation was so bad that the British considered abandoning convoys entirely. The next two months saw a complete reversal of fortunes.
In April, losses of U-boats increased while their kills fell significantly. Only 39 ships of 235,000 tons were sunk in the Atlantic, and 15 U-boats were destroyed. By May, wolf packs no longer had the advantage and that month became known as
Black May in the
U-boat Arm
The (, ) was the navy of Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war (1919–1935) of the Weimar Republic. The was one of three official branches, along with the an ...
(''U-Bootwaffe''). The turning point was the battle centred on slow
convoy ONS 5
ONS 5 was the 5th of the numbered ONS series of Slow trade convoys Outbound from the British Isles to North America. The North Atlantic battle surrounding it in May 1943 is regarded as the turning point of the Battle of the Atlantic in World ...
(April–May 1943). Made up of 43 merchantmen escorted by 16 warships, it was attacked by a pack of 30 U-boats. Although 13 merchant ships were lost, six U-boats were sunk by the escorts or Allied aircraft. Despite a storm which scattered the convoy, the merchantmen reached the protection of land-based air cover, causing Dönitz to call off the attack. Two weeks later,
SC 130 saw at least three U-boats destroyed and at least one U-boat damaged for no losses. Faced with disaster, Dönitz called off operations in the North Atlantic, saying, "We had lost the Battle of the Atlantic".
In all, 43 U-boats were destroyed in May, 34 in the Atlantic. This was 25% of German U-boat Arm's total operational strength. The Allies lost 58 ships in the same period, 34 of these (totalling 134,000 tons) in the Atlantic.
Convergence of technologies
![Submarine attack (AWM 304949)](https://upload.wikimedia.org/wikipedia/commons/f/f1/Submarine_attack_%28AWM_304949%29.jpg)
The Battle of the Atlantic was won by the Allies in two months. There was no single reason for this; what had changed was a sudden convergence of technologies, combined with an increase in Allied resources.
The
mid-Atlantic gap
The Mid-Atlantic gap is a geographical term applied to an undefended area beyond the reach of land-based RAF Coastal Command antisubmarine (A/S) aircraft during the Battle of the Atlantic in the Second World War. It is frequently known as The Bla ...
that had previously been unreachable by aircraft was closed by long-range B-24 Liberators. On 18 March 1943, Roosevelt ordered King to transfer 60 Liberators from the Pacific theatre to the Atlantic to combat German U-boats; one of only two direct orders he gave to his military commanders in WWII (the other was regarding
Operation Torch
Operation Torch (8 November 1942 – Run for Tunis, 16 November 1942) was an Allies of World War II, Allied invasion of French North Africa during the Second World War. Torch was a compromise operation that met the British objective of secu ...
). At the May 1943 Trident conference, Admiral King requested General
Henry H. Arnold
Henry Harley Arnold (June 25, 1886 – January 15, 1950) was an American general officer holding the ranks of General of the Army and later, General of the Air Force. Arnold was an aviation pioneer, Chief of the Air Corps (1938–1941), ...
to send a squadron of ASW-configured B-24s to Newfoundland to strengthen the air escort of North Atlantic convoys. General Arnold ordered his squadron commander to engage only in "offensive" search and attack missions and not in the escort of convoys. In June, General Arnold suggested the Navy assume responsibility for ASW operations. Admiral King requested the Army's ASW-configured B-24s in exchange for an equal number of unmodified Navy B-24s. Agreement was reached in July and the exchange was completed in September 1943.
Further air cover was provided by the introduction of
merchant aircraft carrier
A merchant aircraft carrier (also known as a MAC ship, the Admiralty's official 'short name') was a limited-purpose aircraft carrier operated under British and Dutch civilian registry during World War II. MAC ships were adapted by adding a flig ...
s (MAC ships), and later the growing numbers of American-built escort carriers. Primarily flying
Grumman F4F Wildcat
The Grumman F4F Wildcat is an American carrier-based fighter aircraft that entered service in 1940 with the United States Navy, and the British Royal Navy where it was initially known as the Martlet. First used by the British in the North Atlan ...
s and
Grumman TBF Avenger
The Grumman TBF Avenger (designated TBM for aircraft manufactured by General Motors) is an American World War II-era torpedo bomber developed initially for the United States Navy and Marine Corps, and eventually used by several air and naval av ...
s, they sailed with the convoys and provided much-needed air cover and patrols all the way across the Atlantic.
![U507_under_attack_1943](https://upload.wikimedia.org/wikipedia/commons/3/30/U507_under_attack_1943.jpg)
Larger numbers of escorts became available, both as a result of American building programmes and the release of escorts committed to the North African landings during November and December 1942. In particular,
destroyer escort
Destroyer escort (DE) was the United States Navy mid-20th-century classification for a warship designed with the endurance necessary to escort mid-ocean convoys of merchant marine ships.
Development of the destroyer escort was promoted by th ...
s (DEs) (similar British ships were known as ''
frigate
A frigate () is a type of warship. In different eras, the roles and capabilities of ships classified as frigates have varied somewhat.
The name frigate in the 17th to early 18th centuries was given to any full-rigged ship built for speed and ...
s'') were designed to be built economically, compared to
fleet destroyers and
sloops
A sloop is a sailboat with a single mast typically having only one headsail in front of the mast and one mainsail aft of (behind) the mast. Such an arrangement is called a fore-and-aft rig, and can be rigged as a Bermuda rig with triangular sa ...
whose warship-standards construction and sophisticated armaments made them too expensive for mass production. Destroyer escorts and frigates were also better designed for mid-ocean anti-submarine warfare than
corvettes
A corvette is a small warship. It is traditionally the smallest class of vessel considered to be a proper (or " rated") warship. The warship class above the corvette is that of the frigate, while the class below was historically that of the sloop ...
, which, although maneuverable and seaworthy, were too short, slow, and inadequately armed to match the DEs. Not only would there be sufficient numbers of escorts to securely protect convoys, they could also form hunter-killer groups (often centered on escort carriers) to aggressively hunt U-boats.
By spring 1943, the British had developed an effective sea-scanning radar small enough to be carried in patrol aircraft armed with airborne depth charges.
Centimetric radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weat ...
greatly improved interception and was undetectable by Metox. Fitted with it,
RAF Coastal Command
RAF Coastal Command was a formation within the Royal Air Force (RAF). It was founded in 1936, when the RAF was restructured into Fighter, Bomber and Coastal Commands and played an important role during the Second World War. Maritime Aviation ...
sank more U-boats than any other Allied service in the last three years of the war. During 1943 U-boat losses amounted to 258 to all causes. Of this total, 90 were sunk and 51 damaged by Coastal Command.
Allied air forces developed tactics and technology to make the
Bay of Biscay
The Bay of Biscay (), known in Spain as the Gulf of Biscay ( es, Golfo de Vizcaya, eu, Bizkaiko Golkoa), and in France and some border regions as the Gulf of Gascony (french: Golfe de Gascogne, oc, Golf de Gasconha, br, Pleg-mor Gwaskogn), ...
, the main route for France-based U-boats, very dangerous to submarines. The Leigh Light enabled attacks on U-boats recharging their batteries on the surface at night. ''Fliegerführer Atlantik'' responded by providing fighter cover for U-boats moving into and returning from the Atlantic and for returning
blockade runner
A blockade runner is a merchant vessel used for evading a naval blockade of a port or strait. It is usually light and fast, using stealth and speed rather than confronting the blockaders in order to break the blockade. Blockade runners usuall ...
s. Nevertheless, with intelligence coming from
resistance personnel in the ports themselves, the last few miles to and from port proved hazardous to U-boats.
Dönitz's aim in this tonnage war was to sink Allied ships faster than they could be replaced; as losses fell and production rose, particularly in the United States, this became impossible.
Beginning in August 1943, the British were allowed to access the harbors at the Portuguese Azores Islands and to operate Allied military aircraft based in the Azores Islands.
South Atlantic (May 1942 – September 1943)
Despite U-boat operations in the region (centred in the
Atlantic Narrows
The Atlantic Narrows is a relatively narrow portion of the Atlantic Ocean between South America and West Africa. More specifically, it lies approximately at the Equator where by definition the North Atlantic meets the South Atlantic and roughl ...
between
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
and
West Africa
West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Maurit ...
) beginning autumn 1940, only in the following year did these start to raise serious concern in Washington. This perceived threat caused the US to decide that the introduction of US forces along Brazil's coast would be valuable. After negotiations with Brazilian
Foreign Minister
A foreign affairs minister or minister of foreign affairs (less commonly minister for foreign affairs) is generally a cabinet minister in charge of a state's foreign policy and relations. The formal title of the top official varies between cou ...
Osvaldo Aranha
Oswaldo Euclides de Sousa Aranha (, 15 February 1894 – 27 January 1960) was a Brazilian politician, diplomat and statesman, who came to national prominence in 1930 under Getúlio Vargas.
Considered a moderate by many in and outside of Brazil, ...
(on behalf of dictator
Getúlio Vargas
Getúlio Dornelles Vargas (; 19 April 1882 – 24 August 1954) was a Brazilian lawyer and politician who served as the 14th and 17th president of Brazil, from 1930 to 1945 and from 1951 to 1954. Due to his long and controversial tenure as Brazi ...
), these were introduced in second half of 1941.
Germany and Italy subsequently extended their submarine attacks to include Brazilian ships wherever they were, and from April 1942 were found in Brazilian waters. On 22 May 1942, the first Brazilian attack (although unsuccessful) was carried out by
Brazilian Air Force
"Wings that protect the country"
, colours =
, colours_label =
, march = Hino dos Aviadores
, mascot =
, anniversaries = 22 May (anniver ...
aircraft on the . After a series of attacks on merchant vessels off the Brazilian coast by , Brazil officially entered the war on 22 August 1942, offering an important addition to the Allied strategic position in the South Atlantic.
Although the
Brazilian Navy
)
, colors= Blue and white
, colors_label= Colors
, march= "Cisne Branco" ( en, "White Swan") (same name as training ship ''Cisne Branco''
, mascot=
, equipment= 1 multipurpose aircraft carrier7 submarines6 frigates2 corvettes4 amphibious warf ...
was small, it had modern minelayers suitable for coastal convoy escort and aircraft which needed only small modifications to become suitable for
maritime patrol {{Unreferenced, date=March 2008
Maritime patrol is the task of monitoring areas of water. Generally conducted by military and law enforcement agencies, maritime patrol is usually aimed at identifying human activities.
Maritime patrol refers to ac ...
. During its three years of war, mainly in Caribbean and South Atlantic, alone and in conjunction with the US, Brazil escorted 3,167 ships in 614 convoys, totalling 16,500,000 tons, with losses of 0.1%. Brazil saw three of its warships sunk and 486 men
killed in action (332 in the cruiser ); 972
seamen and civilian passengers were also lost aboard the 32 Brazilian merchant vessels attacked by enemy submarines. American and Brazilian air and naval forces worked closely together until the end of the Battle. One example was the sinking of in July 1943, by a coordinated action of Brazilian and American aircraft.
In Brazilian waters, eleven other Axis submarines were known to be sunk between January and September 1943—the Italian and ten German boats: , , , ''U-507'', , , , , , and .
[
By fall 1943, the decreasing number of Allied shipping losses in the South Atlantic coincided with the increasing elimination of Axis submarines operating there. From then on, the battle in the region was lost by Germany, even though most of the remaining submarines in the region received an official order of withdrawal only in August of the following year, and with (''Baron Jedburgh'') the last Allied merchant ship sunk by a U-boat (''U-532'') there, on 10 March 1945.
]
Final years (June 1943 – May 1945)
Germany made several attempts to upgrade the U-boat force, while awaiting the next generation of U-boats, the Walter
Walter may refer to:
People
* Walter (name), both a surname and a given name
* Little Walter, American blues harmonica player Marion Walter Jacobs (1930–1968)
* Gunther (wrestler), Austrian professional wrestler and trainer Walter Hahn (born 19 ...
and ''Elektroboot
An elektroboot ("electric boat" in German) was a submarine designed to operate entirely submerged, rather than as submersibles that could submerge as a temporary means to escape detection or launch an attack.
History
Even before the Second ...
'' types. Among these upgrades were improved anti-aircraft defences, radar detectors, better torpedoes, decoys, and '' Schnorchel'' (snorkels), which allowed U-boats to run underwater off their diesel engines.
Germany returned to the offensive in the North Atlantic in September 1943 with initial success, with an attack on convoys ONS 18 and ON 202. A series of battles resulted in fewer victories and more losses for ''UbW''. After four months, ''BdU'' again called off the offensive; eight ships of 56,000 tons and six warships had been sunk for the loss of 39 U-boats, a catastrophic loss ratio.
The ''Luftwaffe'' also introduced the long-range He 177
The Heinkel He 177 ''Greif'' (Griffin) was a long-range heavy bomber flown by the ''Luftwaffe'' during World War II. The introduction of the He 177 to combat operations was significantly delayed, by both problems with the development of its ...
bomber and Henschel Hs 293
The Henschel Hs 293 was a World War II German radio-guided glide bomb. It is the first operational anti-shipping missile, first used unsuccessfully on 25 August 1943 and then with increasing success over the next year, ultimately damaging or sink ...
guided glide bomb, which claimed a number of victims, but Allied air superiority prevented them from being a major threat.
German tactical and technical changes
To counter Allied air power, ''UbW'' increased the anti-aircraft armament of U-boats, and introduced specially-equipped "''flak'' boats", which were to stay surfaced and engage in combat with attacking planes, rather than diving and evading. These developments initially caught RAF pilots by surprise. However, a U-boat that remained surfaced increased the risk of its pressure hull being punctured, making it unable to submerge, while attacking pilots often called in surface ships if they met too much resistance, orbiting out of range of the U-boat's guns to maintain contact. Should the U-boat dive, the aircraft would attack. Immediate diving remained a U-boat's best survival tactic when encountering aircraft. According to German sources, only six aircraft were shot down by ''U-flak''s in six missions (three by ''U-441'', one each by ''U-256'', ''U-621'' and ''U-953'').
The Germans also introduced improved radar warning units, such as ''Wanze''. To fool Allied sonar, the Germans deployed ''Bold
In typography, emphasis is the strengthening of words in a text with a font in a different style from the rest of the text, to highlight them. It is the equivalent of prosody stress in speech.
Methods and use
The most common methods in W ...
'' canisters (which the British called Submarine Bubble Target) to generate false echoes, as well as ''Sieglinde
Sieglinde is a Germanic feminine given name. It is derived from two German words or elements. Those being: "sigu" for victory and "lind" for soft, tender, flexible. The diminutive version is "Sigi" or "Siggie".
It is also seen in German mytholog ...
'' self-propelled decoys.
The development of torpedoes also improved with the pattern-running ''Flächen-Absuch-Torpedo'' (FAT
In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food.
The term often refers spec ...
), which ran a pre-programmed course criss-crossing the convoy path and the G7es acoustic torpedo (known to the Allies as German Naval Acoustic Torpedo, GNAT), which homed on the propeller noise of a target. This was initially very effective, but the Allies quickly developed counter-measures, both tactical ("Step-Aside") and technical ("Foxer
Foxer was the code name for a British built acoustic decoy used to confuse German acoustic homing torpedoes like the G7 torpedo during the Second World War. A US version codenamed FXR was deployed at the end of September 1943 on all transatlanti ...
").
None of the German measures were truly effective, and by 1943 Allied air power was so strong that U-boats were being attacked in the Bay of Biscay shortly after leaving port. The Germans had lost the technological race. Their actions were restricted to lone-wolf attacks in British coastal waters and preparation to resist the expected Operation Neptune
Operation or Operations may refer to:
Arts, entertainment and media
* ''Operation'' (game), a battery-operated board game that challenges dexterity
* Operation (music), a term used in musical set theory
* ''Operations'' (magazine), Multi-Man ...
, the invasion of France.
Over the next two years many U-boats were sunk, usually with all hands. With the battle won by the Allies, supplies poured into Britain and North Africa for the eventual liberation of Europe. The U-boats were further critically hampered after D-Day
The Normandy landings were the landing operations and associated airborne operations on Tuesday, 6 June 1944 of the Allied invasion of Normandy in Operation Overlord during World War II. Codenamed Operation Neptune and often referred to as D ...
by the loss of their bases in France to the advancing Allied armies.
Last actions (May 1945)
Late in the war, the Germans introduced the ''Elektroboot'': the Type XXI
Type XXI submarines were a class of German diesel–electric ''Elektroboot'' (German: "electric boat") submarines designed during the Second World War. One hundred and eighteen were completed, with four being combat-ready. During the war only two ...
and short range Type XXIII
German Type XXIII submarines were the first so-called elektroboote ("electric boats") to become operational. They were small coastal submarines designed to operate in the shallow waters of the North Sea, Black Sea and Mediterranean Sea, where la ...
. The Type XXI could run submerged at , faster than a Type VII at full speed surfaced, and faster than Allied corvettes. Designs were finalised in January 1943 but mass-production of the new types did not start until 1944. By 1945, just one Type XXI boat and five Type XXIII boats were operational. The Type XXIIIs made nine patrols, sinking five ships in the first five months of 1945; only one combat patrol was carried out by a Type XXI before the war ended, making no contact with the enemy.
As the Allied armies closed in on the U-boat bases in North Germany, over 200 boats were scuttled to avoid capture; those of most value attempted to flee to bases in Norway. In the first week of May, twenty-three boats were sunk in the Baltic while attempting this journey.
The last actions in American waters took place on May 5–6, 1945, which saw the sinking of the steamer and the destruction of and in separate incidents.
The last actions of the Battle of the Atlantic were on May 7–8. was the last U-boat sunk in action, by an RAF Catalina; while the Norwegian minesweeper and the freighters and were torpedoed in separate incidents, just hours before the German surrender
The German Instrument of Surrender (german: Bedingungslose Kapitulation der Wehrmacht, lit=Unconditional Capitulation of the "Wehrmacht"; russian: Акт о капитуляции Германии, Akt o kapitulyatsii Germanii, lit=Act of capit ...
.
The remaining U-boats, at sea or in port, were surrendered to the Allies, 174 in total. Most were destroyed in ''Operation Deadlight
Operation Deadlight was the code name for the Royal Navy operation of November 1945 – February 1946 to scuttle German U-boats surrendered to the Allies after the defeat of Germany near the end of World War II.
Operation
Of the 156 U-boats ...
'' after the war.
Outcomes
The Germans failed to stop the flow of strategic supplies to Britain. This failure resulted in the build-up of troops and supplies needed for the D-Day landings
The Normandy landings were the landing operations and associated airborne operations on Tuesday, 6 June 1944 of the Allied invasion of Normandy in Operation Overlord during World War II. Codenamed Operation Neptune and often referred to as D ...
. The defeat of the U-boat was a necessary precursor for accumulation of Allied troops and supplies to ensure Germany's defeat.
Victory was achieved at a huge cost: between 1939 and 1945, 3,500 Allied merchant ships (totalling 14.5 million gross tons) and 175 Allied warships were sunk and some 72,200 Allied naval and merchant seamen died. The vast majority of Allied warships lost in the Atlantic and close coasts were small warships averaging around 1,000 tons such as frigates, destroyer escorts, sloops, submarine chasers, or corvettes, but losses also included one battleship (), one battlecruiser (), two aircraft carriers ( and ), three escort carriers (, ''Audacity'', and ), and seven cruisers (, , , , , , and ). The Germans lost 783 U-boats and approximately 30,000 sailors killed, three-quarters of Germany's 40,000-man U-boat fleet. Losses to Germany's surface fleet were also significant, with 4 battleships, 9 cruisers, 7 raiders, and 27 destroyers sunk.
Losses:
Merchant Navy
United Kingdom
During the Second World War nearly one third of the world's merchant shipping was British. Over 30,000 men from the British Merchant Navy
The Merchant Navy is the maritime register of the United Kingdom and comprises the seagoing commercial interests of UK-registered ships and their crews. Merchant Navy vessels fly the Red Ensign and are regulated by the Maritime and Coastguar ...
died between 1939 and 1945. More than 2,400 British ships were sunk. The ships were crewed by sailors from all over the British Empire
The British Empire was composed of the dominions, colonies, protectorates, mandates, and other territories ruled or administered by the United Kingdom and its predecessor states. It began with the overseas possessions and trading posts esta ...
, including some 25% from India and China, and 5% from the West Indies, Middle East and Africa. The British officers wore uniforms very similar to those of the Royal Navy. The ordinary sailors, however, had no uniform and when on leave in Britain they sometimes suffered taunts and abuse from civilians who mistakenly thought the crewmen were shirking their patriotic duty to enlist in the armed forces. To counter this, the crewmen were issued with an 'MN' lapel badge to indicate they were serving in the Merchant Navy.
The British merchant fleet was made up of vessels from the many and varied private shipping lines, examples being the tankers of the British Tanker Company
British Tanker Company Limited was the maritime transport arm of the Anglo-Persian Oil Company, the forerunner of BP. Formed in 1915 with an initial fleet of seven oil tankers, the British Tanker Company became the BP Tanker Company in 1955.
...
and the freighters of Ellerman and Silver
Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...
Lines. The British government, via the Ministry of War Transport
The Ministry of War Transport (MoWT) was a department of the British Government formed early in the Second World War to control transportation policy and resources. It was formed by merging the Ministry of Shipping and the Ministry of Transport ...
(MoWT), also had new ships built during the course of the war, these being known as Empire ship
An Empire ship is a merchant ship that was given a name beginning with "Empire" in the service of the Government of the United Kingdom during and after World War II. Most were used by the Ministry of War Transport (MoWT), which owned them and co ...
s.
United States
In addition to its existing merchant fleet, United States shipyards built 2,710 Liberty ship
Liberty ships were a class of cargo ship built in the United States during World War II under the Emergency Shipbuilding Program. Though British in concept, the design was adopted by the United States for its simple, low-cost construction. Mass ...
s totalling 38.5 million tons, vastly exceeding the 14 million tons of shipping the German U-boats were able to sink during the war.
Canada
Canada's Merchant Navy was vital to the Allied cause during World War II. More than 70 Canadian merchant vessels were lost. An estimated 1,600 merchant sailors were killed, including eight women. Information obtained by British agents regarding German shipping movements led Canada to conscript all its merchant vessels two weeks before actually declaring war, with the Royal Canadian Navy taking control of all shipping August 26, 1939.
At the outbreak of the war, Canada possessed 38 ocean-going merchant vessels. By the end of hostilities, in excess of 400 cargo ships had been built in Canada.
With the exception of the Japanese invasion of the Alaskan Aleutian Islands, the Battle of the Atlantic was the only battle of the Second World War to touch North American shores. U-boats disrupted coastal shipping from the Caribbean to Halifax, during the summer of 1942, and even entered into battle in the Gulf of St. Lawrence.
Canadian officers wore uniforms which were virtually identical in style to those of the British. The ordinary seamen were issued with an 'MN Canada' badge to wear on their lapel when on leave, to indicate their service.
At the end of the war, Rear Admiral Leonard Murray, Commander-in-Chief Canadian North Atlantic, remarked, "...the Battle of the Atlantic was not won by any Navy or Air Force, it was won by the courage, fortitude and determination of the British and Allied Merchant Navy."
Norway
Before the war, Norway's Merchant Navy was the fourth largest in the world and its ships were the most modern. The Germans and the Allies both recognised the great importance of Norway's merchant fleet, and following Germany's invasion of Norway in April 1940, both sides sought control of the ships. Norwegian Nazi puppet leader Vidkun Quisling
Vidkun Abraham Lauritz Jonssøn Quisling (, ; 18 July 1887 – 24 October 1945) was a Norwegian military officer, politician and Nazi collaborator who nominally headed the government of Norway during the country's occupation by Nazi Germ ...
ordered all Norwegian ships to sail to German, Italian or neutral ports. He was ignored. All Norwegian ships decided to serve at the disposal of the Allies. The vessels of the Norwegian Merchant Navy were placed under the control of the government-run Nortraship
The Norwegian Shipping and Trade Mission (Nortraship) was established in London in April 1940 to administer the Norwegian merchant fleet outside German-controlled areas. Nortraship operated some 1,000 vessels and was the largest shipping company ...
, with headquarters in London and New York.
Nortraship's modern ships, especially its tankers, were extremely important to the Allies. Norwegian tankers carried nearly one-third of the oil transported to Britain during the war. Records show that 694 Norwegian ships were sunk during this period, representing 47% of the total fleet. At the end of the war in 1945, the Norwegian merchant fleet was estimated at 1,378 ships. More than 3,700 Norwegian merchant seamen died.
Assessment
It is maintained by G. H. Persall that "the Germans were close" to economically starving England, but they "failed to capitalize" on their early war successes. Others, including Blair and Alan Levine, disagree; Levine states this is "a misperception", and that "it is doubtful they ever came close" to achieving this.
The focus on U-boat successes, the "aces" and their scores, the convoys attacked, and the ships sunk, serves to camouflage the ''Kriegsmarine'' manifold failures. In particular, this was because most of the ships sunk by U-boats were not in convoys, but sailing alone, or having become separated from convoys.
At no time during the campaign were supply lines to Britain interrupted; even during the ''Bismarck'' crisis, convoys sailed as usual (although with heavier escorts). In all, during the Atlantic campaign only 10% of transatlantic convoys that sailed were attacked, and of those attacked only 10% on average of the ships were lost. Overall, more than 99% of all ships sailing to and from the British Isles during World War II did so successfully.
Despite their efforts, the Axis powers were unable to prevent the build-up of Allied invasion forces for the liberation of Europe. In November 1942, at the height of the Atlantic campaign, the US Navy escorted the Operation Torch invasion fleet across the Atlantic without hindrance, or even being detected. (This may be the ultimate example of the Allied practise of evasive routing.) In 1943 and 1944 the Allies transported some 3 million American and Allied servicemen across the Atlantic without significant loss. By 1945 the USN was able to wipe out a wolf-pack suspected of carrying V-weapons in the mid-Atlantic, with little difficulty.
Third, and unlike the Allies, the Germans were never able to mount a comprehensive blockade of Britain. Nor were they able to focus their effort by targeting the most valuable cargoes, the eastbound traffic carrying war materiel. Instead they were reduced to the slow attrition of a tonnage war
A tonnage war is a military strategy aimed at merchant shipping. The premise is that the enemy has a finite number of ships and a finite capacity to build replacements. The concept was made famous by German Grand Admiral Karl Dönitz, who wrote:"T ...
. To win this, the U-boat arm had to sink 300,000 GRT per month in order to overwhelm Britain's shipbuilding capacity and reduce its merchant marine strength.
In only four out of the first 27 months of the war did Germany achieve this target, while after December 1941, when Britain was joined by the US merchant marine and ship yards the target effectively doubled. As a result, the Axis needed to sink 700,000 GRT per month; as the massive expansion of the US shipbuilding industry took effect this target increased still further. The 700,000 ton target was achieved in only one month, November 1942, while after May 1943 average sinkings dropped to less than one tenth of that figure.
By the end of the war, although the U-boat arm had sunk 6,000 ships totalling 21 million GRT, the Allies had built over 38 million tons of new shipping.
The reason for the misperception that the German blockade came close to success may be found in post-war writings by both German and British authors. Blair attributes the distortion to "propagandists" who "glorified and exaggerated the successes of German submariners", while he believes Allied writers "had their own reasons for exaggerating the peril".
Dan van der Vat
Daniel Francis Jeroen van der Vat (28 October 1939 – 9 May 2019) was a journalist, writer and military historian, with a focus on naval history.
Born in Alkmaar, North Holland, Van der Vat grew up in the German- occupied Netherlands. He attended ...
suggests that, unlike the US, or Canada and Britain's other dominions, which were protected by oceanic distances, Britain was at the end of the transatlantic supply route closest to German bases; for Britain it was a lifeline. It is this which led to Churchill's concerns. Coupled with a series of major convoy battles in the space of a month, it undermined confidence in the convoy system in March 1943, to the point Britain considered abandoning it, not realising the U-boat had already effectively been defeated. These were "over-pessimistic threat assessment
Threat assessment is the practice of determining the credibility and seriousness of a potential threat, as well as the probability that the threat will become a reality. Threat assessment is separate to the more established practice of violence-ri ...
s", Blair concludes: "At no time did the German U-boat force ever come close to winning the Battle of the Atlantic or bringing on the collapse of Great Britain".[Blair vol II, p xii]
Shipping and U-boat sinkings each month
Historians disagree about the relative importance of the anti-U-boat measures. Max Hastings
Sir Max Hugh Macdonald Hastings (; born 28 December 1945) is a British journalist and military historian, who has worked as a foreign correspondent for the BBC, editor-in-chief of ''The Daily Telegraph'', and editor of the ''Evening Standard' ...
states that "In 1941 alone, Ultra reaking the German code saved between 1.5 and two million tons of Allied ships from destruction." This would be a 40 percent to 53 percent reduction. A history based on the German archives written for the British Admiralty after the war by a former U-boat commander and son-in-law of Dönitz reports that several detailed investigations to discover whether their operations were compromised by broken code were negative and that their defeat ".. was due firstly to outstanding developments in enemy radar ..." The graphs of the data
In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted ...
are colour coded to divide the battle into three epochs before the breaking of the Enigma code, after it was broken, and after the introduction of centimetric radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weat ...
, which could reveal submarine conning towers above the surface of the water and even detect periscopes. Obviously this subdivision of the data ignores many other defensive measures the Allies developed during the war, so interpretation must be constrained. Codebreaking by itself did not decrease the losses, which continued to rise ominously. More U-boats were sunk, but the number operational had more than tripled. After the improved radar came into action shipping losses plummeted, reaching a level significantly (p=0.99) below the early months of the war. The development of the improved radar by the Allies began in 1940, before the United States entered the war, when Henry Tizard
Sir Henry Thomas Tizard (23 August 1885 – 9 October 1959) was an English chemist, inventor and Rector of Imperial College, who developed the modern "octane rating" used to classify petrol, helped develop radar in World War II, and led the fir ...
and A. V. Hill
Archibald Vivian Hill (26 September 1886 – 3 June 1977), known as A. V. Hill, was a British physiologist, one of the founders of the diverse disciplines of biophysics and operations research. He shared the 1922 Nobel Prize in Physiology or Me ...
won permission to share British secret research with the Americans, including bringing them a cavity magnetron
The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while ...
, which generates the needed high-frequency radio waves.
All sides will agree with Hastings that "... mobilization of the best civilian brains, and their integration into the war effort at the highest levels, was an outstanding British success story."
In popular culture
Films
* '' U-Boote westwärts!'', 1941 propaganda film.
* ''Action in the North Atlantic
''Action in the North Atlantic'', also known as ''Heroes Without Uniforms'', is a 1943 American black-and-white war film from Warner Bros. Pictures, produced by Jerry Wald, directed by Lloyd Bacon, that stars Humphrey Bogart and Raymond Massey a ...
'', 1943 American war film
War film is a film genre concerned with warfare, typically about naval, air, or land battles, with combat scenes central to the drama. It has been strongly associated with the 20th century. The fateful nature of battle scenes means that war fi ...
about sailors aboard a Liberty ship in the US Merchant Marine
United States Merchant Marines are United States civilian mariners and U.S. civilian and federally owned merchant vessels. Both the civilian mariners and the merchant vessels are managed by a combination of the government and private sectors, an ...
battling a German U-boat.
* ''Corvette K-225
''Corvette K-225'' is a 1943 American war film starring Randolph Scott and James Brown, with Ella Raines making her feature film debut. Directed by Richard Rosson, the film was released in the UK as ''The Nelson Touch''. Robert Mitchum, cred ...
'',1943 American film about Royal Canadian Navy convoy escort
* ''Western Approaches
The Western Approaches is an approximately rectangular area of the Atlantic Ocean lying immediately to the west of Ireland and parts of Great Britain. Its north and south boundaries are defined by the corresponding extremities of Britain. The c ...
'', 1944 British colour film dramatising the experience of merchant sailors in a lifeboat.
* '' The Cruel Sea'', 1953 film about a Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
escort during the Battle.
* ''The Enemy Below
''The Enemy Below'' is a 1957 DeLuxe Color war film in CinemaScope about a battle between an American destroyer escort and a German U-boat during World War II. Produced and directed by Dick Powell, the movie stars Robert Mitchum and Curt Jürg ...
'', 1956 film about the captain of an American destroyer escort who matches wits with a German U-boat captain.
* ''Sink the Bismarck!
''Sink the Bismarck!'' is a 1960 black-and-white CinemaScope British war film based on the 1959 book ''The Last Nine Days of the Bismarck'' by C. S. Forester. It stars Kenneth More and Dana Wynter and was directed by Lewis Gilbert.Weiler, A.H ...
'', 1960 film about the hunt for and sinking of the German battleship.
* ''Das Boot
''Das Boot'' (, English: "The Boat") is a 1981 West German war film written and directed by Wolfgang Petersen, produced by Günter Rohrbach, and starring Jürgen Prochnow, Herbert Grönemeyer, and Klaus Wennemann. It has been exhibited both as ...
'', 1981 German film about a German U-boat and its crew.
* '' ''U-571'''', 2000 film about a U-boat boarded by disguised United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
submariners.
* '' In Enemy Hands'', 2004 film about American sailors being taken captive by a German U-boat.
* ''Greyhound
The English Greyhound, or simply the Greyhound, is a breed of dog, a sighthound which has been bred for coursing, greyhound racing and hunting. Since the rise in large-scale adoption of retired racing Greyhounds, the breed has seen a resurge ...
'', 2020 film about an American Commander defending a convoy from U-boats.
Tabletop games
* ''Submarine'', 1976 Avalon Hill
Avalon Hill Games Inc. is a game company that publishes wargames and strategic board games. It has also published miniature wargaming rules, role-playing games and sports simulations. It is a subsidiary of Hasbro, and operates under the company' ...
strategy game.
* ''U-Boat'', 1976 Heritage Models Heritage Models was an American game company that produced role-playing games and game supplements.
History
Wargame company Battleline Publications merged into Heritage USA to speed its growth. Heritage sold off the Battleline operation to Avalon ...
miniatures strategy game.
* ''U-Boat'', 1959 Avalon Hill strategy game.
* ''Wolfpack'', 1974 Simulations Publications, Inc. solitaire strategy game.
* ''War at Sea'', 1975 Avalon Hill strategy game.
Computer games
* ''Aces of the Deep
''Aces of the Deep'' is a World War II submarine simulator game developed by Dynamix for MS-DOS in 1994. The game was re-released by Sierra On-Line for Windows in 1995 as ''Command: Aces of the Deep''. ''Aces of the Deep'' was the last install ...
'', 1994 U-boat simulator video game
* '' Destroyer Command'', 2002 naval simulation
A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of Conceptual model, models; the model represents the key characteristics or behaviors of the selected system or proc ...
video game
* ''Silent Hunter III
''Silent Hunter III'' is a submarine simulation developed by Ubisoft Bucharest and published by Ubisoft. It was released for Windows on March 15, 2005. Like ''Silent Hunter II'', it places the player in command of a Nazi Germany, German U-boat du ...
'', 2005 U-boat simulator video game, third of a series
* '' Silent Hunter 5'', 2010 U-boat simulator video game, fifth of a series
See also
* British merchant seamen of World War II
Merchant seamen crewed the ships of the British Merchant Navy which kept the United Kingdom supplied with raw materials, arms, ammunition, fuel, food and all of the necessities of a nation at war throughout World War II — literally enabling t ...
* British Security Co-ordination
British Security Co-ordination (BSC) was a covert organisation set up in New York City by the British Secret Intelligence Service (MI6) in May 1940 upon the authorisation of the Prime Minister, Winston Churchill.
Its purpose was to investigate ...
* Convoy battles of World War II
* Irish Mercantile Marine during World War II
The Irish Mercantile Marine during World War II continued essential overseas trade in the conflict, a period referred to as The Long Watch by Irish mariners.
Irish merchant shipping saw to it that vital imports continued to arrive and exports, ...
* List of German U-boats in World War II
* List of German U-boats in World War II (1-599)
* List of German U-boats in World War II (600-4712)
{{DEFAULTSORT:German U-boat World War II raiding careers
World War II raiding careers
.U-boat raiding careers
U-boat raiding careers
U-boat ...
* List of wolfpacks of World War II
Wolfpack (naval tactic), Wolfpacks (german: U-Boot-Gruppe) were employed by Nazi Germany's Kriegsmarine during World War II against Allied and neutral shipping.
Outbreak of War
From the outbreak of war until mid-1940 there were various groups of U ...
* Monsun Gruppe
The ''Gruppe Monsun'' or Monsoon Group was a force of German U-boats (submarines) that operated in the Pacific and Indian Oceans during World War II. Although similar naming conventions were used for temporary groupings of submarines in the Atla ...
, the German U-boat campaign in the Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
Notes
References
Bibliography
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* New edition updated with an ''addendum'' consisting of a 1986 paper written by Welchman that corrects his misapprehensions in the 1982 edition.
*
*
Further reading
;Official histories
* Behrens, C.B.A. ''Merchant Shipping and the Demands of War'' London: HMSO)
* Douglas, William A.B., Roger Sarty and Michael Whitby, ''No Higher Purpose: The Official Operational History of the Royal Canadian Navy in the Second World War, 1939–1943'', Volume 2 Part 1, Vanwell Publishing 2002,
* Douglas, William A.B., Roger Sarty and Michael Whitby, ''A Blue Water Navy: The Official Operational History of the Royal Canadian Navy in the Second World War, 1943–1945'', Volume 2 Part 2, Vanwell Publishing 2007,
* Morison, S.E. ''The Two Ocean War'' and ''History of United States Naval Operation in World War II'' in 15 Volumes. Volume I ''The Battle of the Atlantic'' and volume X ''The Atlantic Battle Won'' deal with the Battle of the Atlantic
* Schull, Joseph, ''Far Distant Ships: An Official Account of Canadian Naval Operations in World War II'', King's Printer, Ottawa, 1952 - reprinted by Stoddart Publishing, Toronto, 1987,
Aircraft against U-Boats (New Zealand official history)
;Biographies
* Cremer, Peter. ''U-333''
* Dönitz, Karl. ''Ten Years And Twenty Days''
* Gastaldoni, Ivo. ''A última guerra romântica: Memórias de um piloto de patrulha (The last romantic war: Memoirs of a maritime patrol aviator)'' Incaer, Rio de Janeiro (1993)
* Gretton, Peter. ''Convoy Escort Commander'' (London). Autobiography of a former escort group commander
* Macintyre, Donald. ''U-boat Killer'' (London). Autobiography of another former escort group commander (1956)
* Rayner, Denys, ''Escort: The Battle of the Atlantic'' (London: William Kimber 1955)
* Robertson, Terence. ''The Golden Horseshoe'' (London). Biography of the top German U-boat ace, Otto Kretschmer
Otto Kretschmer (1 May 1912 – 5 August 1998) was a German naval officer and submariner in World War II and the Cold War.
From September 1939 until his capture in March 1941 he sank 44 ships, including one warship, a total of 274,333 tons. For ...
* Robertson, Terence. ''Walker R.N.'' (London 1955). Biography of the leading British escort group commander, Frederick John Walker
Captain (Royal Navy), Captain Frederic John Walker, (3 June 1896 – 9 July 1944) (his first name is given as Frederick in the Oxford Dictionary of National Biography and some London Gazette entries) was a Royal Navy officer noted for his explo ...
* Werner, Herbert A. ''Iron Coffins
Herbert A. Werner (13 May 1920 – 6 April 2013) was a German submarine officer and captain during World War II. He served in five U-boat
U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars ...
'': The account of a surviving U-boat captain with historical and technical details
;General histories of the campaign
*
* Blair, Clay. ''Hitler's U-boat War''. Two volumes. Comprehensive history of the campaign
* Brown, Ken. ''U-Boat Assault on America: Why the US was Unprepared for War in the Atlantic'' (US Naval Institute Press, 2017), 288 pp
*
* Doherty, Richard, 'Key to Victory: The Maiden City in the Battle of the Atlantic'
* Fairbank, David. ''Bitter Ocean: The Battle of the Atlantic, 1939–1945''
* Gannon, Michael. 1990. ''Operation Drumbeat: The Dramatic True Story of Germany's First U-Boat Attacks Along the American Coast in World War II''. Harper and Row.
* Gannon, Michael. 1998. ''Black May: The Epic Story of the Allies' Defeat of the German U-Boats in May 1943''. Dell.
* Haslop, Dennis. ''Britain, Germany and the Battle of the Atlantic: A Comparative Study'' (A&C Black, 2013)
* Keegan, John. ''Atlas of World War II'' (2006)
* Macintyre, Donald. ''The Battle of the Atlantic''. (London 1961). Excellent single volume history by one of the British Escort Group commanders
* Milner, Marc. "The Atlantic War, 1939–1945: The Case for a New Paradigm." ''Global War Studies'' 14.1 (2017): 45–60.
* O'Connor, Jerome M, "FDR's Undeclared War", WWW.Historyarticles.com
* Rohwer, Dr. Jürgen. ''The Critical Convoy Battles of March 1943'' (London: Ian Allan 1977). . A thorough and lucid analysis of the defeat of the U-boats
* Sarty, Roger, ''The Battle of the Atlantic: The Royal Canadian Navy's Greatest Campaign, 1939–1945'', CEF Books, Ottawa, 2001
* Syrett, David. ''The Defeat of the German U-Boats: The Battle of the Atlantic'' (University of South Carolina Press, 1994.)
* Terraine, John, ''Business in Great Waters'', (London 1987) Wordsworth Military Library. The best single-volume study of the U-Boat Campaigns, 1917–1945
* van der Vat, Dan. ''The Atlantic Campaign'', 1988
* Williams, Andrew, ''The Battle of the Atlantic: Hitler's Gray Wolves of the Sea and the Allies' Desperate Struggle to Defeat Them''
External links
U-Boat histories & Fates 1945
The Royal Naval Patrol Service
Battle of the Atlantic 70th Anniversary Commemorations
Navy Department Library, Convoys in World War II: World War II Commemorative Bibliography No. 4, April 1993, AD-A266 529
European Axis Signal Intelligence in World War II as Revealed by "TICOM" Investigations and by other Prisoner of War Interrogations and Captured Material, Principally German: Volume 2 — Notes on German High Level Cryptography and Cryptanalysis
see footnote 3 page 2.
{{DEFAULTSORT:Battle of the Atlantic
American Theater of World War II
Atlantic 1939-45
Campaigns, operations and battles of World War II involving the United Kingdom
Atlantic 1939-45
Atlantic 1939-45
Atlantic 1939-45
Atlantic 1939-45
Atlantic 1939-45
Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...
Atlantic 1939-45
Military history of Canada during World War II
Military history of the Atlantic Ocean
Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...
*
*