Submarine pen

A submarine pen is a bunker to protect moored submarines from air attack.

German World War II U-boat pens in France included Saint-Nazaire, Lorient, La Rochelle and Toulon. In Norway, DORA 1 was a large pen in Trondheim, Norway. U-boat pens protecting construction of the German Type XXI submarine were located at Hamburg (Blohm & Voss), Bremen (AG Weser), and Danzig (F. Schichau). The Finkenwerder U-boat pens were constructed by 1,700 slave labourers over 4 years, and after being captured, were demolished with 32 tonnes of bombs.^[1] U-boat facilities became a bombing priority first in March 1941[1] and again during the Combined Bomber Offensive,^[2][3][4] and U-boat yards and pens were the primary objectives for the Eighth Air Force from late 1942 though early 1943.^[5] Operation Aphrodite guided aircraft, BATTY guided bombs, Disney rocket-boosted bombs, Tallboy bombs and Grand Slam bombs were subsequently used to attack the U-boat pens.

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Gallery of submarine pen images

St. Nazaire U-boat Pens   La Pallice U-boat pen used for the filming of Das Boot   Keroman U-boat Pen

Main article: Combined Bomber Offensive Bombing of U-boat Pens & Yards during World War II
Target	Date	Description
St Nazaire	February 15/16, 1942	10 Armstrong Whitworth Whitleys and 6 Handley Page Halifaxes; only 9 aircraft bombed St Nazaire, in cloudy conditions. No aircraft were lost but 3 crashed in England.[6]
St Nazaire	March 7/8, 1942	17 aircraft bombed St Nazaire[6]
St Nazaire	March 25/26, 1942	Minor Operations: 27 aircraft to St Nazaire -- 1 Vickers Wellington lost[6]
St Nazaire	March 27/28, 1942	35 Whitleys and 27 Wellingtons to bomb German positions around St Nazaire in support of the naval and Commando raid to destroy the dry-dock gates in the port. The aircraft were ordered to bomb only if the target had clear visibility. Conditions were bad, however, with 10/10ths cloud and icing, and only 4 aircraft bombed at St Nazaire; 6 aircraft bombed elsewhere. 1 Whitley was lost in the sea.[6]
St Nazaire	January 3, 1943	The first use of Lt. Col. Curtis LeMay's modification of formation bombing to stagger three-plane elements within a squadron and stagger squadrons within a group was the sixth raid on Saint Nazaire. With LeMay in command of the 305th Bomb Wing, 76 aircraft of 101 dispatched bombers found the target and used a straight and level bomb run. Seven bombers were shot down and forty-seven damaged. The majority of bombloads hit the submarine pens.
Lorient, France	January 15, 1943	The 317th air raid on Lorient dropped 20,000 incendiary bombs.[2]
St Nazaire	January 16, 1943	Two waves of B-17s affected major damage and killed 27 people[2]
Wilhelmshaven	January 27, 1943	VIII Bomber Command dispatched ninety-one B-17s and B-24s to attack the U-Boat construction yards at Wilhemshafen. Only three bombers (1 B-17 and 2 B-24s) were shot down and due to bad weather conditions, only 53 aircraft actually dropped their bombs on the target.
Lorient, France	January 23,26 1942 Feb 3,4,7,13,16 Mar 6 Apr 16 May 17	Lorient was bombed, and the city was evacuated[2]
Bremen	June 3/4, 1942	170 aircraft attacked on the first large raid to Bremen since October 1941. 11 aircraft - 4 Wellingtons, 2 Halifaxes, 2 Lancasters, 2 Stirlings, 1 Manchester - lost. Bremen recorded this as a heavy attack, the results of which exceeded all previous raids. Housing areas were heavily hit with 6 streets affected by serious fires. Damage to the U-boat construction yards and the Focke-Wulf factory is described as 'of no importance' but there were hits in the harbour area which damaged a pier, some warehouses and the destroyer Z-25.[clarification needed] 83 people dead, 29 seriously and 229 slightly injured (Bremen's third heaviest casualty toll in the war).[6]
Wilhelmshaven	June 11, 1943	VIII Bomber Command Mission Number 62: 252 B-17's are dispatched against the U-boat yard at Wilhelmshaven, Germany and the port area at Cuxhaven, Germany; 218 hit the targets; we claim 85-20-24 Luftwaffe aircraft; we lose 8 and 62 are damaged. Casualties are 3 KIA, 20 WIA and 80 MIA. The raid on Wilhelmshaven demonstrates the difficulty of operating beyond range of fighters escort as enemy fighters attacks prevent accurate bombing of the target.[7]
Bremen & Kiel	June 13, 1943	VIII Bomber Command Mission Number 63: 151 B-17's are dispatched against the Bremen U-boat yards; 122 hit the target claiming 2-2-1 Luftwaffe aircraft; we lose 4 and 31 are damaged; casualties are 8 WIA and 32 MIA. A smaller force of 76 B-17's is dispatched against the Kiel, Germany U-boat yards; 60 hit the target and claim 39-5-14 Luftwaffe aircraft; we lose 22, 1 is damaged beyond repair and 23 are damaged; casualties are 3 KIA, 20 WIA and 213 MIA. Heaviest fighter attacks to date against Eighth Air Force accounts for 26 B-17's, mostly of the force attacking Kiel[7]
St. Nazaire	June 28, 1943	VIII Bomber Command Mission Number 69: 191 B-17's are dispatched against the locks and submarine pens at Saint-Nazaire'; 158 hit the target between 1655 and 1713 hours local; we claim 28-6-8 Luftwaffe aircraft; we lose 8 B-17's and 57 others are damaged; casualties are 3 KIA, 14 WIA and 50 MIA[7]
Toulon	November 22, 1943	The 301st Bombardment Group attacked Toulon.[[2]
Toulon	November 24, 1943	Aircraft 25832 (War Bird 11) encountered bad weather enroute to Toulon.[3][4]
Kiel	December, 1943	The B-17/B-24 bombing destroyed one workshop (100%), another workshop and storage building (80%), a factory workship and boat building (67%); damaged a number of other buildings; and hit a submarine under construction and workshops for engines & engineering[5]
Toulon[5]	March 13, 1944	The 9th USAAF raid destroyed U-380.[6]
Kiel	July 23/24, 1944	In the first major raid on a German city for two months, 629 aircraft - 519 Lancasters, 100 Halifaxes, 10 de Havilland Mosquitos - were dispatched in this first RAF raid since April 1943 and the heaviest RAF raid of the war. In a raid lasting only 25 minutes, all parts of Kiel were hit but the bombing was particularly heavy in the port areas and all of the important U-boat yards and naval facilities were hit. The presence of around 500 delayed-action bombs or unexploded duds caused severe problems for the rescue and repair services. There was no water for 3 days; trains and buses did not run for 8 days and there was no gas for cooking for 3 weeks.[6]
Brest	August 5, 1944	15 Avro Lancasters of No. 617 Squadron RAF attacked the Brest U-boat pens and scored 6 direct hits with Tallboy bombs penetrating the concrete roofs. 1 Lancaster was shot down by flak. Subsequent attempts to reinforce other sites with even thicker concrete diverted resources from other projects.[6]
Lorient, France	August 6, 1944	Flight Lieutenant Thomas Clifford Iveson dropped one Tallboy bomb at the Keroman U-boat pen.[8]
Lorient, France	August 7, 1944	The Tallboy bombing mission to Lorient was scrubbed[8]
La Pallice	August 8, 1944	Flight Lieutenant Thomas Clifford Iveson dropped one Tallboy bomb.[8]
La Pallice & Bordeaux	August 11, 1944	53 Lancasters and 3 Mosquitos of No 5 Group attacked U-boat pens at Bordeaux and La Pallice with 2,000lb armour-piercing bombs, but the bombs did not penetrate the roofs. No aircraft lost.[6]
Brest, La Pallice, & Bordeaux	August 12, 1944	68 Lancasters of No 1 Group and 2 Mosquitos of No 5 Group attacked pens at Brest, La Pallice and Bordeaux without loss. A U-boat was believed to have been hit at La Pallice.[6]
Brest	August 13, 1944	28 Lancasters and 1 Mosquito of No 5 Group attacked the U-boat pens and shipping at Brest. Hits were claimed on the pens, on the hulk of an old French battleship, the Clémenceau, and on a medium-sized tanker. The object of the attacks on ships was to prevent the Germans using any of the large ships in Brest to block the harbour just before its capture by American troops. [6]
La Pallice & Bordeaux	August 16, 1944	25 Lancasters and 1 Mosquito of No 5 Group to attack the U-boat pens at La Pallice found the target was cloud-covered and only 3 aircraft bombed. No aircraft lost.[6]
La Pallice	August 17, 1944	Mission 559: A B-17 Flying Fortress dropped BATTY TV bombs on La Pallice.[7] One impacted 1 mile (1.6 km) short and the second about 1 mile to the right of the target.[9]
Ijmuiden	August 28, 1944	Flight Lieutenant Thomas Clifford Iveson dropped one Tallboy bomb.[8]
Heligoland	September 3, 1944	The US Navy controller flew the Operation Aphrodite SAU-1 drone (B-24D 42-63954)[10] into Duene Island by mistake.
Heligoland	September 11, 1944	During the first Castor mission of Operation Aphrodite, the pilot of B-17 42-30180 (Guzzlers) was killed when his parachute failed to open at bailout.[11]
Heligoland	October 15, 1944	Mission 678A:[7] B-17 42-30039 Liberty Belle[7] (differs from 42-30096 'Liberty Belle' lost due to accidental on-board fire and the Liberty Belle (B-17) 44-85734) and B-17 42-37743 of Operation Aphrodite attacked the Heligoland U-boat pens.[11]
Bergen	October 28/29, 1944	237 Lancasters and 7 Mosquitos of No 5 Group attack the U-boat pens at Bergen. The area was cloud-covered and the Master Bomber tried to bring the force down below 5,000 ft but cloud was still encountered and he ordered the raid to be abandoned after only 47 Lancasters had bombed. 3 Lancasters lost.[6]
Heligoland	October 30, 1944	Mission 693A:[7] One Castor Operation Aphrodite drone (B-17 42-30066 MugWump) lost contact and went out of control and crashed near Trollhattan, Sweden. The other drone was B-17 42-3438.[11]
Ijmuiden	December 15, 1944	Flight Lieutenant Thomas Clifford Iveson dropped Tallboy bomb.[8]
Ijmuiden	December 30, 1944	13 Lancasters of No. 617 Squadron RAF set out to bomb the U-boat pens at Ijmuiden but the raid was abandoned because of bad weather.[6]
Ijmuiden	January 12, 1945	No. 617 Squadron RAF attacked the U-boat[8] pens with Tallboy bombs, but smoke obscured the results.[6]
Bergen[8]	January 12, 1945	32 Lancasters and 1 de Havilland Mosquito of No. 9 Squadron RAF and No. 617 Squadron RAF attacked U-boat pens and shipping in Bergen harbour. 3 Lancasters of No 617 Squadron and 1 from No. 9 Squadron RAF were lost; the Germans told the local people that 11 bombers had been shot down. A local report says that 3 Tallboy bombs penetrated the 3½-metre-thick roof of the pens and caused severe damage to workshops, offices and stores inside.[6]
Ijmuiden & Poortershaven	February 3, 1945	36 Lancasters attacked U-boat pens at Ijmuiden (No. 9 Squadron RAF) and Poortershaven (No. 617 Squadron RAF with Tallboy bombs). Hits were claimed at both targets without loss.[6]
Ijmuiden	February 8, 1945	15 Lancasters of No. 617 Squadron RAF dropped Tallboy bombs on the U-boat pens at Ijmuiden without loss.[6]
Ijmuiden	February 10, 1945	Mission 825: 9 of 164 B-17s on a 92nd Bombardment Group mission against the U-boat pens at Ijmuiden, the Netherlands, first used the Royal Navy Disney rocket-boosted concrete piercing bomb.[7]
Oslo Fjord	February 23/24, 1945	73 Lancasters and 10 Mosquitos carried out an accurate attack on a possible U-boat base at Horten on the Oslo Fjord. 1 Lancaster was lost.[6]
Bremen (Farge)[12]	March 27, 1945	20 Lancasters of No. 617 Squadron RAF attacked the Valentin submarine pens,[13] and two Grand Slam bombs penetrated two metres and detonated[13], which rendered the shelter unusable. No aircraft were lost.[6]
Bremen	March 30, 1945	303rd BG (H) Combat Mission No. 348: 38 aircraft were dispatched to bomb Bremen. The submarine building yards were the first priority target.(PDF)
Hamburg/Finkenwarde	April 4, 1945	99.0 tonnes of bombs used[8]
Hamburg	April 9, 1945	17 aircraft of No. 617 Squadron RAF, with Grand Slam and Tallboy bombs, successfully attacked the U-boat shelters. No aircraft were lost.[6]
Kiel	April 9/10, 1944	591 Lancasters and 8 Mosquitos of Nos 1, 3 and 8 Groups to Kiel. 3 Lancasters lost. This was an accurate raid, made in good visibility on two aiming points in the harbour area. Photographic reconnaissance showed that the Deutsche Werke U-boat yard was severely damaged, the German pocket battleship Admiral Scheer was hit and capsized, the German cruiser Admiral Hipper and the German cruiser Emden were badly damaged. The local diary says that all 3 shipyards in the port were hit and that the nearby residential areas were severely damaged.[6]
Kiel	April 13/14, 1944	377 Lancasters and 105 Halifaxes of Nos 3, 6 and 8 Groups to Kiel. 2 Lancasters lost. This raid was directed against the port area, with the U-boat yards as the main objective. RAF Bomber Command rated this as 'a poor attack' with scattered bombing.[6]
Heligoland	April 18, 1945	969 aircraft - 617 Avro Lancasters, 332 Handley Page Halifaxes, 20 de Havilland Mosquitos of all groups - successfully used attacked the Naval base, airfield, & town "almost into crater-pitted moonscapes"[14]. 3 Halifaxes were lost,[6] and the islands were evacuated the following night.
Heligoland	April 19, 1945	No. 9 and 617 Squadrons RAF use Tallboy bombs against "coastal battery positions"[14]

References