Battle Of Drøbak Sound

The Battle of Drøbak Sound took place in Drøbak Sound, the northernmost part of the outer Oslofjord in southern Norway, on 9 April 1940. It marked the end of the "Phoney War" and the beginning of World War II in Western Europe.

A German fleet led by the cruiser '' Blücher'' was dispatched up the Oslofjord to begin the German invasion of Norway, with the objective of seizing the Norwegian capital of Oslo and capturing King Haakon VII and his government. The fleet was engaged in the fjord by Oscarsborg Fortress, an aging coastal installation near Drøbak, that had been relegated to training coastal artillery servicemen, leading the Germans to disregard its defensive value. However, unbeknownst to German military intelligence, the fortress' most powerful weapon was a torpedo battery, which would be used to great effect against the German invaders.

The fortress' armaments worked flawlessly despite their age, sinking the ''Blücher'' in the sound and forcing the German fleet to fall back. The loss of the German flagship, which carried most of the troops and Gestapo agents intended to occupy Oslo, delayed the German occupation long enough for King Haakon VII and his government to escape from the capital.

Before the battle

Norway

Oscarsborg Fortress was commanded by 64-year-old ''Oberst'' (Colonel) Birger Eriksen. He had not received clear orders and no information on whether the approaching warships were German or Allied. He knew that Norway was officially neutral but that the government was inclined to side with the British if Norway became a belligerent.

The fortress' main command station and battery was on Håøya island north-west of South Kaholmen (.) Due to the special circumstances in 1940, Eriksen commanded from the backup station at South Kaholmen, east of the main battery.

Apart from the officers and NCOs, most of the remaining garrison consisted of 450 fresh troops conscripted on 2 April. The naval mines were not deployed; deployment was scheduled for a few days after 9 April as a recruit training exercise.

The main battery consisted of three Krupp guns called ''Moses'', ''Aron''Hauge 1995: 35 and ''Josva''. There were enough trained gunners for one gun. They were split between two guns and assisted by non-combatant privates including cooks. All the guns were loaded with live high-explosive shells.

The fortress' torpedo battery was armed with 40-year-old Austro-Hungarian Whitehead torpedoes. The weapons had been practice-launched over 200 times; despite doubts they functioned properly during the battle. The battery had three launch tunnels opening below the surface. There were six torpedoes ready to launch, and another nine as reloads.

The torpedo battery was commanded by '' Kommandørkaptein'' (Commander Senior Grade) , who lived in Drøbak. He was a temporary substitute for the commanding officer who went on sick leave in March 1940. Late on 8 April during the action in the Oslofjord, Eriksen ordered Anderssen to the battery; Anderssen donned his old uniform and was transported across the fjord to the battery by boat. Anderssen was familiar with the post; he first served at the battery in 1909 and was its commander by the time he retired in 1927. Anderssen was recalled to active duty in March.

Germany

The objective of the German naval force was to capture the Norwegian capital, Oslo, King Haakon VII, and the Norvegian government. It was led by the cruiser '' Blücher'', a new warship with an inexperienced crew. Those onboard included ''Generalmajor'' Erwin Engelbrecht, Admiral Oskar Kummetz and a special unit for capturing the king.

The Germans underestimated the operational value of the Norwegian coastal fortifications; the fortifications were old and used for training. The Germans did not know of the Oscarsborg torpedo battery.

Battle

The main battery fires

At 04:21 on 9 April, Eriksen ordered the main battery to fire on ''Blücher'', the lead ship of the German flotilla heading to Oslo. When his command was questioned, Eriksen replied: "Either I will be decorated or I will be court martialled. Fire!" Firing without warning shots violated the pre-war Norwegian rules of engagement. The German ships had already received warning and live shots from outlying fortifications; Erikson later used this to justify his decision to consider the ships to be hostile.

Two guns, ''Moses'' and ''Aron'', each fired one high-explosive shell.Hauge 1995: 35 The first shell struck the front of the mainmastRibsskog 1998: 50 and set the midship area up to the fore mast on fire; this detonated a magazine containing stores for the Arado Ar 196 reconnaissance floatplanes - oil cans, smoke dispensers, incendiary bombs, aircraft bombs and depth charges. Shortly after the first hit, the second shell hit the base of one of the forward gun turrets, throwing debris from it overboard and igniting further fires;Ribsskog 1998: 51 this put the ship's main guns out of action by disabling their electrical power. The unmanned third gun, ''Josva'', was not fired. No further shells were fired; the guns could not be reloaded in time with the untrained gunners.

The secondary batteries fire

Next, the secondary Norwegian coastal batteries opened fire on ''Blücher''. The weapons ranged from two small guns at Husvik, intended to protect the fortress' missing mine barrier, to the three guns of the KopÃ¥s Battery on the eastern side of the fjord. The 57 mm guns targeted the cruiser's superstructure and anti-aircraft (AA) weapons,Fjeld2 1999:36 and partially suppressed German return fire. ''Blücher'' continued to sail slowly northward. It passed close enough to fire on the Husvik battery with light AA guns. The Norwegians abandoned Husvik; its main building caught fire but there were no casualties. In all, the cruiser was hit by thirteen 15 cm and around thirty 57 mm shells. One 15 cm hit from KopÃ¥s disabled the steering gear; the ship avoided grounding by steering with its engines. Shell fragments disabled the firefighting system.Fjeld2 1999:36

The fortress' gun batteries had been in action for only five to seven minutes. Return fire from ''Blücher''s light battery was ineffective due to excessive elevation.Binder 2001: 77

At this point, Germans voices on the cruiser became audible to the Norwegians, alerting the latter of their opponent's identity;Berg 1997: 12–13 according to the Norwegians, the Germans began to sing ''Deutschlandlied'', the German national anthem.Hauge 1995: 36Tamelander&Zetterling 2001: 87Berg 1997: 13 The Norwegian minesweeper HNoMS ''Otra'' had identified the intruders as Germans earlier and communicated this to the Horten naval base at 04:10. Norwegian communications problems delayed its delivery to Oscarsborg; Eriksen received it at 04:35. There was then "a dead silence on board the whole ship, no movement whatsoever was identified".

The torpedo battery fires

''Blücher'' was crippled but remained afloat. It continued to move north, which brought it within of Oscarsborg's torpedo battery. Anderssen fired the first torpedo at about 04:30. The target's speed was slightly overestimated and the torpedo struck near the ship's forward turret and caused inconsequential damage. The aim was corrected for the second torpedo; it struck amidship in the same area as the first 28 cm shell hit. The hit disabled the engines,Hauge 1995: 38 blew open bulkheads and caused flooding. The ship continued to burn.

The fortress' third torpedo tube was not fired in case of further targets. The other tubes were reloaded.

''Blücher'' sinks

''Blücher'' anchored near the Askholmene islets just north and out of the field of fire of the fort's guns. The crew attempted to fight the uncontrolled fires. Torpedoes were fired to prevent their detonation by the fires. At 05:30,Hauge 1995: 38 the fires detonated a midship magazine for the ''Flak'' guns, blowing a hole in the ship's sideWilliamson 2003: 33–34 ruptured the bulkheads between the boiler rooms, and caused further fires by opening fuel tanks.

''Blücher'' sank bow-first at 06:22, capsizing to port. Two thousand German sailors and soldiers were in the freezing water. Hundreds died when floating fuel oil caught fire.

According to survivor ''Obergefreiter'' Günther Morgalla, as he swam ashore he heard someone defiantly singing the ''Deutschlandlied'' followed by "''Das kann doch einen Seemann nicht erschüttern''" ("''That cannot shake a sailor''").Binder 2001: 89

Approximately 1,400 Germans survived and 650–800 died. 1,200 came ashore at Frogn near Drøbak. 550 were captured by His Majesty the King's Guard, 4th Company, commanded by '' Kaptein'' (Captain) A. J. T. Petersson. The guardsmen were supposed to take all the Germans prisoner, but mainly focused on treating casualties. Around 1,000 Germans, including Engelbrecht and Kummetz, were eventually moved to a nearby farm and placed under light guard. The prisoners were not interrogated, and were effectively freed when the Norwegians withdrew by 18:30. Engelbrecht and Kummetz reached Oslo at 22:00, establishing themselves in the Hotel Continental, and occupying the capital with their remaining troops. Norwegian wounded and many German wounded were treated by the Royal Norwegian Navy Hospital at the Asgården summer hotel in Åsgårdstrand; the hospital had been evacuated from Horten at midnight on 8 April.

Remaining ships retreat

When ''Blücher'' was hit by the torpedoes, the commander of the heavy cruiser ''Lützow'' - unaware of the torpedo battery - assumed the presence of mines. At 04:40, the Germans decided to withdraw and land their troops out of range of the Oscarsborg guns. The attack on Oslo would continue by a landward advance up the Oslofjord.

The retreating ''Lützow'' was hit by three 15 cm shells from the KopÃ¥s battery which disabled the cruiser's forward 28 cm turret. KopÃ¥s continued to fire until the German ships disappeared into the mist at a range of around . ''Lützow''s aft turret bombarded the Norwegians from a range of down the fjord.

The first Norwegian civilian ship lost during the invasion, the Norwegian cargo cutter , was sunk during the battle. ''Sørland'' was carrying paper from Moss to Oslo when it stumbled into the battle which it thought was an exercise. It was attacked and set on fire by the German minesweepers ''R-18'' and ''R-19'' and sank near Skiphelle in Drøbak with the loss of two of its six crew. The burning ship was misidentified by the Norwegians as the German training ship . The real ''Brummer'' was lost in connection with the invasion. It was torpedoed on 14 April by the Royal Navy submarine while returning to Germany and sank the next day.

''Luftwaffe'' bombing

The fortress was heavily bombed for nearly nine hours by the ''Luftwaffe'' later that day. The fortress' AA weapons were two Bofors 40 mm L/60 cannon, three Colt M/29 machine guns at the Seiersten Battery, four Colt M/29 7.92 mm machine guns at the main battery, and four machine guns at the main battery. There were no Norwegian casualties, but the main battery machine guns were abandoned early on. One Bofors became unserviceable after only 22 rounds; the other kept firing - to little effect - until 12:00 when the air attacks paused. ''Lützow'' bombarded Hovedøya until 13:30 when the air attacks resumed with bombers strafing the Norwegian AA guns. Around 14:00, the guns went out-of-action when their crews took cover in the nearby forest.Fjeld 1999: 191

The air attacks included 22 long-range Junkers Ju 87R "Stuka" dive bombers of '' Sturzkampfgeschwader 1'', commanded by ''Hauptmann'' Paul-Werner Hozzel, operating from Kiel-Holtenau airport in northern Germany. Around 500 bombs — ranging from in size — were dropped.

Surrender

The Norwegian situation continued to deteriorate. The Germans took Oslo later in the day with troops airlifted into Fornebu Airport, and additional landings occurred at the village of Son south of Drøbak. Eriksen decided that there was inadequate infantry to continue fighting. He agreed to a ceasefire on the evening of 9 April, and surrendered the fortress intact on the morning of 10 April.Fjeld 1999: 192

The garrison went into captivity. The enlisted and NCOs of the secondary batteries were released three days later; those of the main battery a week later. The officers were initially taken to Fredriksten Fortress, with the reservists being released on 15 May. Regular officers were moved again to the Grini detention camp and released in late-May 1940.

Aftermath

The destruction of ''Blücher'' by the Oscarsborg Fortress and the withdrawal of the German naval force caused a significant delay in the German capture of Oslo. The delay allowed King Haakon VII, Prime Minister Johan Nygaardsvold's government, the parliament and the gold reserve to be evacuated. As the Norwegians retreated, the government was granted wartime emergency powers by the king and parliament; the affirmations included the Elverum Authorization of 9 April. The government maintained this legitimacy when it became a government-in-exile in the United Kingdom on 7 June shortly before the Norwegian Army surrendered on 10 June.

Media adaption

The battle is depicted in the 2016 feature film '' The King's Choice''.

See also

* List of Norwegian military equipment of World War II
* List of German military equipment of World War II

References

Bibliography

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*Binder, Frank & Schlünz Hans Hermann: ''Schwerer Kreuzer Blücher'', Koehlers Verlagsgesellschaft mbH, Hamburg 2001
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(to be quoted as Fjeld2 1999)
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* Williamson, Gordon: ''German Heavy Cruisers 1939–45'', Osprey Publishing Ltd., Oxford 2003

External links

Oscarsborg Fortress Museum official website

Oscarsborg Fortress websiteWebsite on the fortress

Oscarsborg Fortress, map
Norwegian Defence Estates Agency
Oscarsborg Museum – history of the fortress

Norwegian Armed Forces website page about the fortress

50 year anniversary Aftenposten newspaper article on the invasion of Norway

{{DEFAULTSORT:Drobak Sound 1940
Naval battles of World War II involving Norway
Naval battles of World War II involving Germany
Norwegian campaign
1940 in Norway
History of Akershus
Frogn
April 1940 in Europe
Oslofjord
Naval bombing operations and battles of World War II
Building bombings in Norway
Attacks on military installations in Norway
Aerial operations and battles of World War II involving Germany
Attacks on military installations in 1940