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The Battle of the Ruhr (5 March – 31 July 1943) was a
strategic bombing Strategic bombing is a military strategy used in total war with the goal of defeating the enemy by destroying its morale, its economic ability to produce and transport materiel to the theatres of military operations, or both. It is a systematica ...
campaign against the
Ruhr Area The Ruhr ( ; german: Ruhrgebiet , also ''Ruhrpott'' ), also referred to as the Ruhr area, sometimes Ruhr district, Ruhr region, or Ruhr valley, is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 2,800/km ...
in
Nazi Germany Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...
carried out by
RAF Bomber Command RAF Bomber Command controlled the Royal Air Force's bomber forces from 1936 to 1968. Along with the United States Army Air Forces, it played the central role in the strategic bombing of Germany in World War II. From 1942 onward, the British bo ...
during 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 ...
. The Ruhr was the main centre of German
heavy industry Heavy industry is an industry that involves one or more characteristics such as large and heavy products; large and heavy equipment and facilities (such as heavy equipment, large machine tools, huge buildings and large-scale infrastructure); o ...
with coke plants, steelworks, armaments factories and ten synthetic oil plants. The British attacked 26 targets identified in the
Combined Bomber Offensive The Combined Bomber Offensive (CBO) was an Allies of World War II, Allied offensive of strategic bombing during World War II, strategic bombing during World War II in Europe. The primary portion of the CBO was directed against Luftwaffe targets w ...
. Targets included the Krupp armament works (
Essen Essen (; Latin: ''Assindia'') is the central and, after Dortmund, second-largest city of the Ruhr, the largest urban area in Germany. Its population of makes it the fourth-largest city of North Rhine-Westphalia after Cologne, Düsseldorf and D ...
), the Nordstern
synthetic oil Synthetic oil is a lubricant consisting of chemical compounds that are artificially modified or synthesised. Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be syn ...
plant at Gelsenkirchen and the
Rheinmetal Rheinmetall AG is a German automotive and arms manufacturer, headquartered in Düsseldorf, Germany. Its shares are traded on the Frankfurt stock exchange. History Rheinmetall was founded in 1889. Banker and investor Lorenz Zuckermandel L ...
Borsig Borsig is a surname. Notable people with the surname include: * (1867–1897), German entrepreneur * August Borsig (1804–1854), German businessman * Conrad von Borsig (1873–1945), German mechanical engineer * Ernst Borsig Ernst August Pau ...
plant in
Düsseldorf Düsseldorf ( , , ; often in English sources; Low Franconian and Ripuarian: ''Düsseldörp'' ; archaic nl, Dusseldorp ) is the capital city of North Rhine-Westphalia, the most populous state of Germany. It is the second-largest city in th ...
, which was evacuated during the battle. The battle included cities such as
Cologne Cologne ( ; german: Köln ; ksh, Kölle ) is the largest city of the German western States of Germany, state of North Rhine-Westphalia (NRW) and the List of cities in Germany by population, fourth-most populous city of Germany with 1.1 m ...
not in the Ruhr proper but which were in the larger
Rhine-Ruhr The Rhine-Ruhr metropolitan region (german: Metropolregion Rhein-Ruhr) is the largest metropolitan region in Germany, with over ten million inhabitants. A polycentric conurbation with several major urban concentrations, the region covers ...
region and considered part of the Ruhr industrial complex. Some targets were not sites of heavy industry but part of the production and movement of
materiel Materiel (; ) refers to supplies, equipment, and weapons in military supply-chain management, and typically supplies and equipment in a commercial supply chain context. In a military context, the term ''materiel'' refers either to the specifi ...
. The Ruhr had been attacked by Bomber Command from 1940, its defences and the amounts of industrial pollutants produced a semi-permanent
smog Smog, or smoke fog, is a type of intense air pollution. The word "smog" was coined in the early 20th century, and is a portmanteau of the words ''smoke'' and '' fog'' to refer to smoky fog due to its opacity, and odor. The word was then inte ...
that hampered bomb aiming. Along with the active defences of anti-aircraft guns, searchlights and night fighters, the Germans built large night-time decoys such as the
Krupp decoy site The Krupp decoy site (German: Kruppsche Nachtscheinanlage) was a German decoy-site of the Krupp steel works in Essen. During World War II, it was designed to divert Allied airstrikes from the actual production site of the arms factory. Descri ...
() near
Essen Essen (; Latin: ''Assindia'') is the central and, after Dortmund, second-largest city of the Ruhr, the largest urban area in Germany. Its population of makes it the fourth-largest city of North Rhine-Westphalia after Cologne, Düsseldorf and D ...
to
spoof Spoof, spoofs, spoofer, or spoofing may refer to: * Forgery of goods or documents * Semen, in Australian slang * Spoof (game), a guessing game * Spoofing (finance), a disruptive algorithmic-trading tactic designed to manipulate markets __NOTOC__ ...
the bombers into hitting the open country. Cities outside the Ruhr were attacked to prevent the Germans from concentrating their defences and before the end of the battle,
Operation Gomorrah The Allied bombing of Hamburg during World War II included numerous attacks on civilians and civic infrastructure. As a large city and industrial centre, Hamburg's shipyards, U-boat pens, and the Hamburg-Harburg area oil refineries were attacke ...
on 24 July 1943 began the Battle of Hamburg. After the turn to Hamburg, Bomber Command continued to raid the Ruhr to keep the German defences dispersed.


Background


Bomber Command, 1942

In 1942 some answers to the chronic problems of night navigation and target finding began to emerge but the number of bombers had stagnated. In November 1941 Bomber Command had a daily average of 506 bombers available and in January 1943 the average was 515. To carry out the Thousand-bomber raids Bomber Command drew on crews and aircraft from the Operational Training Units, which could only be exceptional. Navigation had been helped by the introduction of Gee but this device lacked accuracy for bombing through the dark and smog of the Ruhr, lacked range and from 4 August 1942 the Germans began to
jam Jam is a type of fruit preserve. Jam or Jammed may also refer to: Other common meanings * A firearm malfunction * Block signals ** Radio jamming ** Radar jamming and deception ** Mobile phone jammer ** Echolocation jamming Arts and entertai ...
the device. The
Pathfinder Force The Pathfinders were target-marking squadrons in RAF Bomber Command during World War II. They located and marked targets with flares, which a main bomber force could aim at, increasing the accuracy of their bombing. The Pathfinders were norma ...
(PFF) was established on 15 August 1942 but with Gee jammed and no
target indicator Target indicators, also known as target markers or TI's for short, were flares used by the RAF's Bomber Command during World War II. TIs were normally dropped by Pathfinders onto the target, providing an easily seen visual aiming point for the ...
bombs to mark the aiming point for the rest of the bombers (the Main Force), the task of the PFF varied from thankless to impossible. Despite its problems, Bomber Command had been able to achieve some spectacular results but these had been isolated events and due to favourable circumstances as well as judgement. The loss of 1,404 aircraft and 2,724 damaged to German night defences of increasing quantity and quality, especially German
night fighter A night fighter (also known as all-weather fighter or all-weather interceptor for a period of time after the Second World War) is a fighter aircraft adapted for use at night or in other times of bad visibility. Night fighters began to be used i ...
s () had become a serious threat to the viability of the command and of strategic bombing as a theory of war. In 1942 Bomber Command had created 19 new squadrons but 13 had been transferred to other commands. The quantity of aircraft had barely increased but a big improvement in quality had been achieved.
Bristol Blenheim The Bristol Blenheim is a British light bomber aircraft designed and built by the Bristol Aeroplane Company (Bristol) which was used extensively in the first two years of the Second World War, with examples still being used as trainers until ...
light bombers and
Armstrong Whitworth Whitley The Armstrong Whitworth A.W.38 Whitley was a British medium bomber aircraft of the 1930s. It was one of three twin-engined, front line medium bomber types that were in service with the Royal Air Force (RAF) at the outbreak of the Second World ...
medium bombers had been retired from the command in mid-1942, followed by the
Handley Page Hampden The Handley Page HP.52 Hampden is a British twin-engine medium bomber that was operated by the Royal Air Force (RAF). It was part of the trio of large twin-engine bombers procured for the RAF, joining the Armstrong Whitworth Whitley and Vickers ...
medium bomber in September. The disappointments of the
Short Stirling The Short Stirling was a British four-engined heavy bomber of the Second World War. It has the distinction of being the first four-engined bomber to be introduced into service with the Royal Air Force (RAF). The Stirling was designed during t ...
and the early
Handley Page Halifax The Handley Page Halifax is a British Royal Air Force (RAF) four-engined heavy bomber of the Second World War. It was developed by Handley Page to the same specification as the contemporary twin-engine Avro Manchester. The Halifax has its or ...
variants and the fiasco of the
Avro Manchester The Avro 679 Manchester was a British twin-engine heavy bomber developed and manufactured by the Avro aircraft company in the United Kingdom. While not being built in great numbers, it was the forerunner of the famed and vastly more successful ...
, withdrawn in June 1942, was balanced by the
Avro Lancaster The Avro Lancaster is a British Second World War heavy bomber. It was designed and manufactured by Avro as a contemporary of the Handley Page Halifax, both bombers having been developed to the same specification, as well as the Short Stirlin ...
, which made its operational début in March and demonstrated its superiority over all other bombers. Re-equipment with new types of aircraft led to an average of 16.36 per cent of Bomber Command squadrons withdrawn from operations for conversion onto new aircraft in 1942, against 3.3 per cent in 1943. On 1 January 1942 the command had 48 squadrons, 9 with heavy bombers, 34 with medium and five with light bombers (Blenheims). On 1 January 1943, there were 49 squadrons, 32 heavy, 11 medium and six light (
de Havilland Mosquito The de Havilland DH.98 Mosquito is a British twin-engined, shoulder-winged, multirole combat aircraft, introduced during the Second World War. Unusual in that its frame was constructed mostly of wood, it was nicknamed the "Wooden Wonder", or ...
). The command had flown 30,508 operational sorties in 1941 and dropped of bombs, in 1942 it dropped from 29,929 sorties.


Gee

Gee worked by wireless signals transmitted from three ground stations in England, on a line about long, being displayed on a cathode ray tube to the navigator and placed on a Gee chart, giving a fix of the aircraft's position in less than a minute. Accuracy varied from and Gee had a range of , accuracy falling with distance. Gee worked well as a homing device but early hopes of it being accurate enough for blind bombing were not realised. Crews appreciated the value of the apparatus for navigation on the return journey, removing the fear of flying into hills and other obstructions. By August 1942, 80 per cent of the bomber force was equipped and 100 per cent by January 1943. Coverage of the Ruhr was known as the eastern chain and later northern and southern chains were added. Gee was usually ineffective east of the Ruhr and was easy to jam, which began on 4 August 1942, from when Gee fixes were only obtainable over the North Sea and parts of France. Gees loss of accuracy with distance made it a better target-finding device for raiders over Britain. The signals were encoded to prevent German use but this made it harder for Bomber Command navigators to get Gee fixes. Anti-jamming devices were short-lived in effectiveness as the Germans quickly overcame them but Gee Mk II was easier for navigators to use.


Oboe

Oboe was a blind-bombing device controlled by two ground stations in England which measured the distance of an aircraft from them with radar pulses. Cat tracked the aircraft over the target and Mouse calculated the point on the track where the aircraft should bomb. Oboe transmissions did not follow the curvature of the earth, making the altitude of the aircraft the determinant of range. An aircraft flying at could receive Oboe transmissions at about , enough to mark targets in the Ruhr, which led to the device being installed in fast, high-flying Mosquito bombers, which usually navigated with the usual aids until beginning an Oboe run about from the target. Use of the Mosquito made an Oboe run safer, even when no evasive action could be taken before bombing. Accuracy was measured in hundreds of yards which increased with greater experience of the aircrews and ground operators. Oboe could be jammed and suffer interference from Monica and other Bomber Command devices. Oboe Mk I operated on a frequency of 1.5 metres, K Oboe was in general use from mid-June 1943 and was free from jamming. Centimetric Oboe Mk II and Mk III retained the effectiveness of Oboe until the end of the war but are beyond the scope of this article; rushing Oboe Mk I into service delayed Mk II but jamming did not begin until August 1943. Cat and Mouse stations could handle only one aircraft at a time and a marking run took ten minutes, allowing six bomb- or marker-runs per hour. The illumination from a Target Indicator bomb usually lasted for six minutes, guaranteeing four-minute gaps in marking. A failed marking run increased the gap to fourteen minutes. The introduction of multi-channel control and more ground stations eventually increased the concentration of Oboe marking. From the introduction of Oboe in December 1942 until the end of the war, Oboe aircraft made 9,624 sorties on 1,797 raids.


1943

At the beginning of 1943, the political resolve of the British government to support the bomber offensive remained and more resources had been provided. A plan to create a 4,000-strong bomber force had been abandoned as unrealisable but the diversion of Bomber Command squadrons to
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 ...
and overseas commands was constrained and its expansion continued. A blind bombing device,
Oboe The oboe ( ) is a type of double reed woodwind instrument. Oboes are usually made of wood, but may also be made of synthetic materials, such as plastic, resin, or hybrid composites. The most common oboe plays in the treble or soprano range. A ...
, had been introduced on the night of 20/21 December 1942, H2S, a ground-scanning radar, on 30/31 January and a new target indicator bomb had come into service on 16/17 January. The new devices and the increase in the number of heavy bombers promised a large improvement in the quantity of bombs dropped and in accuracy of aim. For the first time since day bombing was abandoned in 1940, Bomber Command was released from the constraints occasioned by the adoption of night bombing. The tactical use of the new devices was developed quickly but the new equipment had limitations. Oboe had a range which was little beyond the Ruhr and research on repeater aircraft to extend its range was stopped because H2S was expected to be a better system and only a few aircraft could use the device simultaneously; although Oboe had the potential for a vast improvement in target finding, it was not of pinpoint accuracy. H2S could be installed on any aircraft but was complicated, difficult to use and emitted radiation which could be detected, paradoxically exposing the aircraft to interception. Gee remained useful as a means of navigation on return journeys but required development to overcome German jamming.


Target Indicator bomb

The Target Indicator bomb (TI) was an aerodynamic metal case which ejected coloured pyrotechnic candles at a set height by a barometric fuze. If set to ignite immediately they made a cascade. When sky marking, the candles were on parachutes and if fuzed for ground burst, they created a pool of coloured fire. The usual TI covered an area on the ground of about and a ground burst TI contained some candles which were explosive, to deter attempts to extinguish them. The TI was introduced on the night of 16/17 January 1943 and was a great success, making pathfinding a practical operation of war.


H2S

H2S was a device for navigation and blind bombing by radar. The emissions of the radar were reflected and received as echoes which were distinctive of the earth below. Built-up areas returned echoes different from fields and forests, land echoes could be distinguished from the sea and sea echoes from those of a ship. The radar had a scanner which swept vertically and the echoes were detected by a receiver and displayed on a
cathode-ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), pictur ...
, with a sweep rotating at the same speed as the scanner, giving an impression of the earth below. The contrast between water and land made coasts, lakes and rivers particularly recognisable. Towns also stood out and sometimes railway lines, from which the navigator could determine his position. When closer to the target, if it was recognisable, an H2S bombing run could be made; if the target could not be distinguished the bomber could make a timed run from a landmark in the vicinity. Since the device was airborne its range was limited only to that of its aircraft. The apparatus was limited by echoes from towns and cities which were harder to distinguish than those from countryside and town. H2S was inferior to Oboe for blind bombing except on coastal targets like
Hamburg (male), (female) en, Hamburger(s), Hamburgian(s) , timezone1 = Central (CET) , utc_offset1 = +1 , timezone1_DST = Central (CEST) , utc_offset1_DST = +2 , postal ...
. Being a transmitter, H2S disclosed itself to the Germans as soon as enough parts had been recovered from shot-down bombers to analyse its characteristics. German detectors could find a bomber stream and direct night-fighters into it. Once Bomber Command began to use centimetric H2S in January 1943 it was inevitable that the Germans would retrieve one from a crashed bomber and realise that it was similar to
Air-to-Surface Vessel radar Radar, Air-to-Surface Vessel, or ASV radar for short, is a classification used by the Royal Air Force (RAF) to refer to a series of aircraft-mounted radar systems used to scan the surface of the ocean to locate ships and surfaced submarines. The fi ...
(ASV) used by Coastal Command to detect surfaced submarines. In October 1943, beyond the scope of this article, the Germans introduced the
Naxos radar detector The Naxos radar warning receiver was a World War II German countermeasure to S band microwave radar produced by a cavity magnetron. Introduced in September 1943, it replaced Metox, which was incapable of detecting centimetric radar. Two versions ...
in night-fighters and U-boats. By mid-January 1943, only 10 Halifax bombers and 13 Stirlings carried H2S; the rate of production was slow and by May 1943, no more than 18 H2S-equipped bombers had participated in one raid; by August 840 H2S sets had been manufactured.


Prelude


German air defences

The threat of Anglo-American strategic bombing had been a concern to German strategists since 1940 at the latest. After the
Fall 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 German invasion of France during the Second World ...
, a belt of
Freya radar Freya was an early warning radar deployed by Germany during World War II; it was named after the Norse goddess Freyja. During the war, over a thousand stations were built. A naval version operating on a slightly different wavelength was also d ...
stations was built to give early warning of aircraft entering German-controlled airspace, from
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
south to
Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
. Freya lacked the accuracy needed for ground-controlled interception of aircraft and was supplemented later in 1940 by
Würzburg radar The low-UHF band Würzburg radar was the primary ground-based tracking radar for the Wehrmacht's Luftwaffe and Kriegsmarine (German Navy) during World War II. Initial development took place before the war and the apparatus entered service in 1940 ...
stations which were accurate enough to guide FlaK and night fighters, a -guided FlaK battery shooting down a bomber in September 1940. In October (Colonel)
Josef Kammhuber Josef Kammhuber (August 19, 1896 – January 25, 1986) was a career officer in the Luftwaffe and post-World War II German Air Force. During World War II, he was the first general of night fighters in the Luftwaffe. Kammhuber created the night ...
established three night-fighter zones on the approaches to the Ruhr. The zones were long and wide, with a battalion of searchlights and two radars in each. A night-fighter could be guided to within of an aircraft and then attack when the aircraft was illuminated by the searchlights, a procedure called ( lluminated night fighting. Forward zones were established along the coast, without searchlights, known as (
ark Nightfighting Ark or ARK may refer to: Biblical narratives and religion Hebrew word ''teva'' * Noah's Ark, a massive vessel said to have been built to save the world's animals from a flood * Ark of bulrushes, the boat of the infant Moses Hebrew ''aron'' * ...
. The system lacked effectiveness on cloudy nights, the range of the radar [] was too short and it could not Identification friend or foe, Identify friend or foe, which led occasionally to attacks on friendly night fighters; some night fighter crews disliked ground control for the loss of flexibility. The German system had not been centralised to sift the information provided by radar, searchlights, wireless interception and direction finding to co-ordinate FlaK and night-fighters. To the end of 1940, the new system was credited with the shooting down of 42 bombers by night fighters and 30 by FlaK. They system was extended with a line of about wide which, by March 1941, ran from the Danish–German frontier to
Maubeuge Maubeuge (; historical nl, Mabuse or nl, Malbode; pcd, Maubeuche) is a commune in the Nord department in northern France. It is situated on both banks of the Sambre (here canalized), east of Valenciennes and about from the Belgian border ...
in France. Another belt long was built between
Frankfurt Frankfurt, officially Frankfurt am Main (; Hessian: , "Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on its na ...
and
Mannheim Mannheim (; Palatine German: or ), officially the University City of Mannheim (german: Universitätsstadt Mannheim), is the second-largest city in the German state of Baden-Württemberg after the state capital of Stuttgart, and Germany's 2 ...
later in the year. Three guided the searchlights to illuminate bombers as they entered the zone. were extended in circumference and the chain was extended along the coasts of France and the Low Countries and around Berlin. Late in 1941 an improved with a -range and the
Seeburg plotting table {{unreferenced, date=January 2022 The Seeburg plotting table ( German: ''Seeburg-Tisch'') was a mechanical plotting table used by Nazi Germany in their operation rooms to track aircraft and coordinate operations during World War II. Attached to t ...
() came into service. Kammhuber used the new equipment to revise the night defence system by increasing the width of from with in front of them. Kammhuber intended to introduce behind the
Kammhuber Line The Kammhuber Line was the Allied name given to the German night air defense system established in July 1940 by Colonel Josef Kammhuber. It consisted of a series of control sectors equipped with radars and searchlights and an associated night fig ...
, placed stations on either side and installed master searchlights. The system was introduced in September but proved to be too complex and the number of interceptions decreased. In the spring of 1942 the depth of the belt of searchlights was reduced to and widened to . A new (combined) method was intended to counter the new and faster four-engined bombers coming into service with Bomber Command but the risk of the FlaK shooting down night-fighters was too great and the system was a failure. In 1941, Bomber Command losses rose to 3.6 per cent from the 2.9 per cent of 1940. During a raid on Berlin on the night of 7/8 November, 12.4 per cent of the 169 bombers were shot down. The night-fighter force shot down 433 bombers and by the end of the year, nine and one were in action. The confused and overlapping jurisdictions of the German defence against night attacks were exacerbated by the lack of effectiveness of the British night bomber offensive and this complacency was not shaken by the entry of the United States into the war in December. Because of the diversion of night-fighters to the Eastern front and the Mediterranean, by February 1942, there were 265 night-fighters in the west, of an establishment of 367, only half of which were operational. The British resorted to a deliberate campaign of
area bombing In military aviation, area bombardment (or area bombing) is a type of aerial bombardment in which bombs are dropped over the general area of a target. The term "area bombing" came into prominence during World War II. Area bombing is a form of str ...
which immediately increased the amount of destruction achieved by Bomber Command. The bomb tonnage increased from 37,000 in 1941 to 50,000 in 1942. The German night defence was not prepared for the change in British methods and the introduction of GEE, the first night navigation aid. The British ended the individual timing of bomber sorties in favour of the concentration of all the bombers in space and time, which made most of the Kammhuber Line redundant, leaving only a few fighters able to attack the bombers. On the 1,000-bomber raid on Cologne, the bombers spent only two hours over Europe, the stream was wide and only 25 night-fighters could engage the bombers, just over ten per cent of the total; bomber losses fell from 3.6 to 3.0 per cent. In 1942, Bomber Command had been able to inflict considerable damage on several occasions but had failed consistently to disrupt the German war economy.


During 1942, the night-fighter command organisation abolished its for three on 1 May and by February 1943, 477 night-fighters were available from an establishment of 653, of which 330 were operational, double that of 1942, 90 per cent of which were in the west. Nearly all of the night-fighters carried Lichtenstein, an Airborne Interception radar (AI), with a maximum range of and a minimum range of , sufficient to track a bomber after ground control had brought the night-fighter to within . Despite the weight of the apparatus and aerodynamic penalty of its aerial array causing a loss of at least in speed, night-fighter interceptions increased to the extent that searchlight illumination was made redundant and the lights were transferred to the local FlaK units around cities. By June the Kammhuber Line had been extended southwards towards Paris and northwards to the north coast of Denmark. Kammhuber refused to allow night-fighters to roam freely but made the line more flexible, by deepening the zone to either side of the to exploit the increased range of and , which created the system. In each sector, one tracked the bomber and another the night-fighter until it was close enough for the crew to use its AI for the attack. A zone was limited to one night-fighter but they overlapped by 50 per cent, enabling three night-fighters to operate in one area. GEE was jammed from August, limiting its usefulness to no further than the European coast. Much of the airspace of Europe remained undefended and bomber streams made all but a few night-fighters ineffective, which limited the capacity of German night defences to shoot down no more than about 6 per cent of Bomber Command sorties. The German night defences managed to shoot down 687 bombers in 1942, 63 per cent more than in 1941 for a loss of 97 night-fighters, 63 per cent more than in 1941 and on 10 September shot down its 1,000th bomber, 649 by , 200 by , 140 by intruder operations over Britain and 11 bombers crashed after being blinded by searchlights. Night-fighters and FlaK were shooting down an average of 5.6 per cent of Bomber Command aircraft per raid by the autumn. The performance of FlaK also showed an improvement, from July to August 1942, Bomber Command reported the loss of 696 bombers, 269 thought to have been destroyed by night-fighters, 193 by FlaK and 334 loses to unknown causes; 1,394 aircraft were damaged, 153 were hit by night-fighters and 941 by FlaK. By the end of the year, the had faced 77,500 night sorties, shooting down 2,859 bombers, a rate of 3.6 per cent and damaged far more. In 1940 Bomber Command lost a bomber crashed in Britain for every 32 sorties and in 1942 the rate had increased to one in twenty. To the end of 1942, the had dropped of bombs on Britain and the RAF had dropped on Germany and on the occupied territories. According to post-war research by the Allies, bombing cut German production by 0.7 to 2.5 per cent in 1942, compared to the devotion of 33 per cent of the British war economy to the bomber offensive. Despite the big increase in the German anti-aircraft effort, such concern for the future as existed did not prevent 150 FlaK batteries from being transferred to Italy. Only the ,
Erhard Milch Erhard Milch (30 March 1892 – 25 January 1972) was a German general field marshal (''Generalfeldmarschall'') of Jewish heritage who oversaw the development of the German air force (''Luftwaffe'') as part of the re-armament of Nazi Germany foll ...
, in charge of aircraft production, foresaw the crisis that would ensue if fighter output was not given greater emphasis. The advent of British four-engined bombers had increased by 70 per cent the bomb tonnage carried by Bomber Command. Milch predicted that the Anglo-American air fleets would swamp the German air defences and destroy the war economy. On 21 March 1942, Milch advocated to
Hermann Göring Hermann Wilhelm Göring (or Goering; ; 12 January 1893 – 15 October 1946) was a German politician, military leader and convicted war criminal. He was one of the most powerful figures in the Nazi Party, which ruled Germany from 1933 to 1 ...
, commander in chief of the and
Hans Jeschonnek Hans Jeschonnek (9 April 1899 – 18 August 1943) was a German military aviator in the ''Luftstreitkräfte'' during World War I, a general staff officer in the ''Reichswehr'' in the inter–war period and ''Generaloberst'' (Colonel-General) and a ...
, the chief of staff of (High Command of the Air Force) the creation of an air umbrella. Milch told Goering that his target of 360 new fighters per month would be insufficient even if it were increased to 3,600, which Jeschonnek dismissed by saying that he would not know what to do with 360 new fighters a month. During the spring of 1943, the Germans increased the ground anti-aircraft defences in the Ruhr; by July there were more than 1,000 large FlaK (anti-aircraft) guns (
88 mm gun The 8.8 cm Flak 18/36/37/41 is a German 88mm anti-aircraft and anti-tank artillery gun, developed in the 1930s. It was widely used by Germany throughout World War II and is one of the most recognized German weapons of the conflict. Develo ...
s or larger) and 1,500 lighter guns (most being 20 mm and 37 mm) about a third of the anti-aircraft guns in Germany, which needed 600,000 men, women and boys to operate.


Ruhr

The Ruhr industrial region enclosed the valleys of the
Ruhr The Ruhr ( ; german: Ruhrgebiet , also ''Ruhrpott'' ), also referred to as the Ruhr area, sometimes Ruhr district, Ruhr region, or Ruhr valley, is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 2,800/km ...
and
Wupper The Wupper is a right tributary of the Rhine in the state of North Rhine-Westphalia, Germany. Rising near Marienheide in western Sauerland it runs through the mountainous region of the Bergisches Land in Berg County and enters the Rhine at Lever ...
rivers and was from east to west and from north to south, enclosing an area of about . Most of the valleys had been built over by fourteen towns creating a
conurbation A conurbation is a region comprising a number of metropolises, cities, large towns, and other urban areas which through population growth and physical expansion, have merged to form one continuous urban or industrially developed area. In most ca ...
covering , with a population of about 4,115,000. The most industrialised area lay between Dortmund and Duisburg covered an area of with 3,000,000 of the Ruhr population. The region was the most industrial in Germany, with 71 per cent of the output of coking coal and 61.5 per cent of its pig iron and steel and 67 per cent of the special steels essential in the rest of the German economy. From 1940, many foreign workers, prisoners of war and slave labourers were brought to the
Krupp The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
works at
Essen Essen (; Latin: ''Assindia'') is the central and, after Dortmund, second-largest city of the Ruhr, the largest urban area in Germany. Its population of makes it the fourth-largest city of North Rhine-Westphalia after Cologne, Düsseldorf and D ...
, already a city of 670,000 people. The main Krupp works in the Essen town centre covered , a subsidiary on the edge of town another and from 1940 became important targets of the British strategic bombing strategy. The mining industries of the region employed another 16 per cent of the population. The most important towns were Essen,
Cologne Cologne ( ; german: Köln ; ksh, Kölle ) is the largest city of the German western States of Germany, state of North Rhine-Westphalia (NRW) and the List of cities in Germany by population, fourth-most populous city of Germany with 1.1 m ...
and
Duisburg Duisburg () is a city in the Ruhr metropolitan area of the western German state of North Rhine-Westphalia. Lying on the confluence of the Rhine and the Ruhr rivers in the center of the Rhine-Ruhr Region, Duisburg is the 5th largest city in Nor ...
, site of the largest inland port in Europe. In 1941, Krupps had built the
Krupp decoy site The Krupp decoy site (German: Kruppsche Nachtscheinanlage) was a German decoy-site of the Krupp steel works in Essen. During World War II, it was designed to divert Allied airstrikes from the actual production site of the arms factory. Descri ...
() at
Velbert Velbert ( Low Rhenish: ''Vèlbed'') is a town in the district of Mettmann, in the German state of North Rhine-Westphalia. The town is renowned worldwide for the production of locks and fittings. Geography Velbert is located on the hills of 'Niede ...
south of Baldney See, with illumination suggesting a poorly blacked-out industrial site and railway goods yards. The decoy was successful before the advent of British night navigation and blind bombing devices late in 1942 and early 1943. On the outskirts of Essen there were hydrogenation plants close to the
Gelsenkirchen Gelsenkirchen (, , ; wep, Gelsenkiärken) is the 25th most populous city of Germany and the 11th most populous in the state of North Rhine-Westphalia with 262,528 (2016) inhabitants. On the Emscher River (a tributary of the Rhine), it lies ...
-Benzin works at Nordstern and at Buer which had an output of of aviation fuel a year. Before 1943, Krupps had been hit by 48 bombs and 1,515 incendiaries and the decoy site by 70 bombs and 5,665 incendiaries.


Battle


Operation Chastise, 16/17 May 1943

Operation Chastise was a special operation carried out during the battle to disrupt the Ruhr by attacking its sources of water and hydroelectric power.
617 Squadron Number 617 Squadron is a Royal Air Force aircraft squadron, originally based at RAF Scampton in Lincolnshire and currently based at RAF Marham in Norfolk. It is commonly known as "''The Dambusters''", for its actions during Operation Chastis ...
was formed in secret and trained at short notice to attack the dams above the Ruhr with special bombs. Nineteen Lancasters in three waves were dispatched. Six bombers did not reach the dams (one turning back after losing its bomb and five were shot down). Twelve Lancasters bombed, five against the
Möhne Dam The Möhne () is a river in North Rhine-Westphalia, Germany. It is a right tributary of the Ruhr. The Möhne passes the towns of Brilon, Rüthen and Warstein. There is a large artificial lake near the mouth of the river, the Möhne Reservoir, us ...
, three the Eder Dam, two the
Sorpe Dam The Sorpe Dam (german: Sorpetalsperre) is a dam on the Sorpe river, near the small town of Sundern in the district of Hochsauerland in North Rhine-Westphalia, Germany. Together with the Biggesee, the Möhne Reservoir, and the Verse reservoir ...
and one the Schwelme Dam. The Möhne and Eder were breached. The Mohne Reservoir was an important supplier of water to the Ruhr and the flooding caused much damage to road, rail and canals, leading to electricity and water shortages, rationing being necessary until the autumn rains. The Eder Dam was larger but was distant from the Ruhr and the breach had more effect on
Kassel Kassel (; in Germany, spelled Cassel until 1926) is a city on the Fulda River in northern Hesse, Germany. It is the administrative seat of the Regierungsbezirk Kassel and the district of the same name and had 201,048 inhabitants in December 2020 ...
and its vicinity. The Sorpe Dam was only slightly damaged and was able to keep the Ruhr operating during the repairs to the Möhne. Three more aircraft were lost on the return flight, 53 aircrew were killed and three taken prisoner. There were 1,294 civilian casualties, 859 occurring at
Neheim-Hüsten Arnsberg (; wep, Arensperg) is a town in the Hochsauerland county, in the German state of North Rhine-Westphalia. It is the location of the Regierungsbezirk Arnsberg administration and one of the three local administration offices of the Hochs ...
where 493 female Ukrainian
slave labour Slavery and enslavement are both the state and the condition of being a slave—someone forbidden to quit one's service for an enslaver, and who is treated by the enslaver as property. Slavery typically involves slaves being made to perf ...
ers were drowned; another 58 bodies were found around the Eder Dam.


Other targets

Bomber Command raided cities outside the Ruhr during the battle to prevent the Germans from concentrating their defences. On the night of 1/2 March
Berlin Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ...
was attacked by 302 bombers and on the night of 3/4 March Hamburg was raided by 417 bombers.
Nuremberg Nuremberg ( ; german: link=no, Nürnberg ; in the local East Franconian dialect: ''Nämberch'' ) is the second-largest city of the German state of Bavaria after its capital Munich, and its 518,370 (2019) inhabitants make it the 14th-largest ...
was bombed on the night of 8/9 March by 335 bombers. On the night of 9/10 March
Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...
was raided by 264 bombers and 314 bombers hit
Stuttgart Stuttgart (; Swabian: ; ) is the capital and largest city of the German state of Baden-Württemberg. It is located on the Neckar river in a fertile valley known as the ''Stuttgarter Kessel'' (Stuttgart Cauldron) and lies an hour from the ...
on the night of 11/12 March. Berlin was visited on the night of 27/28 March by 396 bombers and again on 29/30 March by 329 bombers.
Kiel Kiel () is the capital and most populous city in the northern Germany, German state of Schleswig-Holstein, with a population of 246,243 (2021). Kiel lies approximately north of Hamburg. Due to its geographic location in the southeast of the J ...
was bombed by 577 aircraft on the night of 4/5 April and Frankfurt am Main was bombed by 502 aircraft on the night of 10/11 April. Bomber Command attacked Stuttgart with 562 bombers on the night of 14/15 April. On the night of 16/17 April Bomber Command conducted a raid on Pilsen, on 20/21 April Stettin (now
Szczecin Szczecin (, , german: Stettin ; sv, Stettin ; Latin: ''Sedinum'' or ''Stetinum'') is the capital and largest city of the West Pomeranian Voivodeship in northwestern Poland. Located near the Baltic Sea and the German border, it is a major s ...
) was bombed by 304 aircraft and on the night of 13/14 May, Pilsen was bombed again. In June, raids outside the Ruhr consisted of a 72-aircraft attack on
Münster Münster (; nds, Mönster) is an independent city (''Kreisfreie Stadt'') in North Rhine-Westphalia, Germany. It is in the northern part of the state and is considered to be the cultural centre of the Westphalia region. It is also a state distr ...
during the night of 11/12 June followed by 60 bombers against
Friedrichshafen Friedrichshafen ( or ; Low Alemannic: ''Hafe'' or ''Fridrichshafe'') is a city on the northern shoreline of Lake Constance (the ''Bodensee'') in Southern Germany, near the borders of both Switzerland and Austria. It is the district capital (''Kre ...
on the night of 20/21 June.
Aachen Aachen ( ; ; Aachen dialect: ''Oche'' ; French and traditional English: Aix-la-Chapelle; or ''Aquisgranum''; nl, Aken ; Polish: Akwizgran) is, with around 249,000 inhabitants, the 13th-largest city in North Rhine-Westphalia, and the 28th- ...
was bombed by 374 aircraft on the night of 13/14 July.


Aftermath


Analysis

In 1956 the New Zealand official historian, Henry Thompson, wrote that at Essen, after more than 3,000 sorties and the loss of 138 aircraft, the " Krupp works...and the town...itself contained large areas of devastation" and Krupp did not resume locomotive production after the second March raid. The battle demonstrated the increasing power of Bomber Command. Targets that hitherto been invulnerable were severely damaged and this appeared to be feasible on targets inside Oboe range. Earlier successes had depended on the weather and occasional opportunities that could not be replicated. Harris saw the Battle of the Ruhr as a beginning and that more cities in Germany would have to be devastated and that the Ruhr would have to be attacked again to keep repaired factories out of production. In 1981 Matthew Cooper wrote that the most significant event in 1943 for the was the increase in strategic bombing, the RAF and USAAF dropping of bombs, more than 300 per cent of the 1942 total. Bomber Command dropped of bombs in area attacks and killed about 181,000 civilians. Essen in the Ruhr was attacked on 5/6 March with of bombs, the first of the 43 attacks of the Battle of the Ruhr. The British dispatched 18,506 sorties against targets marked by Oboe, accurate to , dropping about of bombs. In one raid, in fifteen minutes, 90 per cent of Wuppertal-Barmen was destroyed and 2,450 people killed. On 10 April, after visiting Essen to see for himself,
Josef Goebbels Paul Joseph Goebbels (; 29 October 1897 – 1 May 1945) was a German Nazi politician who was the ''Gauleiter'' (district leader) of Berlin, chief propagandist for the Nazi Party, and then Reich Minister of Propaganda from 1933 to 194 ...
, the Propaganda Minister, wrote in his diary, Goebbels blamed Göring and
Ernst Udet Ernst Udet (26 April 1896 – 17 November 1941) was a German pilot during World War I and a ''Luftwaffe'' Colonel-General (''Generaloberst'') during World War II. Udet joined the Imperial German Air Service at the age of 19, and eventually ...
, the chief of procurement, for negligence on a grand scale. On 8 May, Hitler told Milch that either tactics or technology was lacking and after meeting Hitler on the same day, Goebbels wrote, By June the night-fighter force had been increased to 18 , five more than at the start of the year but the system limited the number of night-fighters over the Ruhr to 36. FlaK that had been diverted to Italy and the Eastern Front was recalled and new batteries of two or three FlaK batteries () assembled at important targets to counter the shorter time that the bombers were over the target. The Ruhr FlaK was doubled to 400 batteries of heavy FlaK, with more
105 mm 1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. I ...
and 128 mm anti-aircraft guns, comprising about 40 per cent of the FlaK in Germany. In May, Kammhuber made a claim for a night-fighter force of 2,160 aircraft, especially if the US bombers turned to night bombing but Hitler refused to listen. Göring accepted Kammhuber's analysis on 6 July after more evidence of the effectiveness of RAF bombing but by then it was too late. On the night of 24/25 July the Allied bombers began the Battle of Hamburg using H2S, a new navigation aid and jammed German radars with
Window A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent materia ...
( to the Germans) against which no countermeasures had been prepared, neutralising the system. In the informal German official history ''
Germany and the Second World War ''Germany and the Second World War'' (german: Das Deutsche Reich und der Zweite Weltkrieg) is a 12,000-page, 13-volume work published by the Deutsche Verlags-Anstalt (DVA), that has taken academics from the military history centre of the German ...
'' (1990–2018) Horst Boog wrote that by late July Harris thought that the Ruhr has been reduced to chaos, that German arms production had been substantially cut and that the morale of the population had been undermined but the Germans had already begun to disperse industry. Bomber Command had created much more destruction in Essen in 1943 with 5.6 per cent of the Bomber Command effort (3,261 sorties) and 138 losses against the 10 per cent (3,724 sorties) and 201 losses of 1942. Bomber Command overestimated its effect but achieved a reduction of four to six weeks of German industrial output. In its 43 raids on the Ruhr, Bomber Command dispatched about 18,500 bomber sorties for a loss of 872 (4.7 per cent) of the aircraft and 6,000 aircrew; another 2,126 aircraft were damaged, sometimes beyond recovery. The average loss rate was 5 per cent, with losses, damaged and losses not caused by the German anti-aircraft defences (crashed in England due to weather, damaged aircraft written off and crewmembers wounded or killed in returned aircraft) was 16 per cent during the campaign. Oboe was a success and aircraft production exceeded losses, realising a net increase from 663 aircraft in March 1943 to 776 in July. In his 2006 study of the German war economy,
Adam Tooze John Adam Tooze (born 1967) is an English historian who is a professor at Columbia University, Director of the European Institute and nonresident scholar at Carnegie Europe. Previously, he was Reader in Twentieth-Century History at the Universi ...
wrote that Bomber Command severely disrupted German production during the battle. Contemporary sources show that the bombing was a watershed in the development of the German war economy, which has been severely underestimated by later accounts. The Ruhr was the most important source of coking coal and steel in Europe and the main source of components; cutting production in the Ruhr disrupted production all over Germany. The status of the Ruhr was changed from that of the home front to a war zone with an emergency staff placed to control over the regional economy. Workers were accommodated in camps, ready to be sent to factories that were still open but these were expedients. The German night defences could not stop the British from inflicting great disruption on the war economy. Steel production was cut by when
Albert Speer Berthold Konrad Hermann Albert Speer (; ; 19 March 1905 – 1 September 1981) was a German architect who served as the Minister of Armaments and War Production in Nazi Germany during most of World War II. A close ally of Adolf Hitler, he ...
, head of the
Reich Ministry of Armaments and War Production The Reich Ministry of Armaments and War Production () was established on March 17, 1940, in Nazi Germany. Its official name before September 2, 1943, was the 'Reichsministerium für Bewaffnung und Munition' (). Its task was to improve the sup ...
, was expecting output to increase to , causing a deficit of . Having reorganised the steel allocation system, the German planners were forced into a large cut in the ammunition production programme to compensate. After a doubling of ammunition production in 1942, output increased by only 20 per cent in 1943. All over Germany, the destruction in the Ruhr caused shortages of parts, castings and forgings, a (sub-components crisis), which reached far beyond heavy industry. From July 1943 to March 1944, there were no increases in monthly aircraft production for the and in the rest of the armaments economy there was no increase in production until 1944. "Bomber Command had stopped Speer's armaments miracle in its tracks", despite the loss of 640 bombers and most of their crews, yet Bomber Command increased in size between February and August 1943 due to the increase in output of the British aircraft industry.


Casualties

In 1961, Webster and Frankland, in their official history ''The Strategic Air Offensive against Germany 1939–1945'' (volume II), recorded that in February 1943, Bomber Command had an average of 593 crews and aircraft available for operations and 787 in August. During the battle, Ruhr targets were raided 43 times on 39 nights. Bomber Command dispatched 18,506 sorties, in which 872 aircraft failed to return and 2,126 were damaged, with 6,000 aircrew casualties. Some aircraft were badly enough damaged to amount to the loss of the aircraft and crew. The casualty rate (of all natures) was 16 per cent of sorties, 4.7 per cent being losses over Germany. Of 203 Mosquito bomber sorties, two aircraft were lost and from 282 Oboe-Mosquito sorties, there were two losses and six damaged. In 2006, Adam Tooze wrote that the German night defences had inflicted great damage on Bomber Command, shooting down or causing to crash 640 bombers and killing nearly 4,000 aircrew.


Dams raid

Operation Chastise had a temporary effect on industrial production, through the disruption of the water supply and
hydroelectric power Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...
. The Eder Valley dam did not supply the
Ruhr Area The Ruhr ( ; german: Ruhrgebiet , also ''Ruhrpott'' ), also referred to as the Ruhr area, sometimes Ruhr district, Ruhr region, or Ruhr valley, is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 2,800/km ...
. A spare pumping system had been built for the Ruhr and
Organisation Todt Organisation Todt (OT; ) was a civil and military engineering organisation in Nazi Germany from 1933 to 1945, named for its founder, Fritz Todt, an engineer and senior Nazi. The organisation was responsible for a huge range of engineering projec ...
rapidly mobilized workers from the construction of the
Atlantic Wall The Atlantic Wall (german: link=no, Atlantikwall) was an extensive system of coastal defences and fortifications built by Nazi Germany between 1942 and 1944 along the coast of continental Europe and Scandinavia as a defence against an anticip ...
to make repairs. Destruction of the Sorpe Dam would have caused significantly more damage but it was a stronger design and less likely to be breached and it had been made a secondary target. Of the crews on the raid, 53 were killed and three taken prisoner. There were 1,294 casualties, 859 at Neheim-Hüsten where 493 female Ukrainian slave labourers were drowned; another 58 bodies were found around the Eder Dam.


Notes


Footnotes


References

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Further reading

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External links

* {{DEFAULTSORT:Ruhr, Battle of the World War II strategic bombing Aerial operations and battles of World War II involving Canada Aerial operations and battles of World War II involving the United Kingdom Conflicts in 1943 Germany in World War II ms:Pertempuran Ruhr