Bundesarchiv Bild 101II-MW-3676-28, St. Nazaire, Uboot U 552.jpg
Erich Topp (r) on U-552 in St. Nazaire in October 1941
Nazi Germany
Ordered25 September 1939
BuilderBlohm & Voss, Hamburg
Yard number528
Laid down1 December 1939
Launched14 September 1940
Commissioned4 December 1940
DecommissionedFebruary 1945
FateScuttled on 5 May 1945 at Wilhelmshaven
General characteristics
Class and typeType VIIC submarine
  • 769 tonnes (757 long tons) surfaced
  • 871 t (857 long tons) submerged
  • 6.20 m (20 ft 4 in) o/a
  • 4.70 m (15 ft 5 in) pressure hull
Height9.60 m (31 ft 6 in)
Draught4.74 m (15 ft 7 in)
Installed power
  • 2,800–3,200 PS (2,100–2,400 kW; 2,800–3,200 bhp) (diesels)
  • 750 PS (550 kW; 740 shp) (electric)
  • 17.7 knots (32.8 km/h; 20.4 mph) surfaced
  • 7.6 knots (14.1 km/h; 8.7 mph) submerged
  • 8,500 nmi (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph) surfaced
  • 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth
  • 230 m (750 ft)
  • Crush depth: 250–295 m (820–968 ft)
Complement4 officers, 40–56 enlisted
Service record
Part of:
Identification codes: M 20052
  • K.Kapt. Erich Topp
  • 4 December 1940 – 8 September 1942
  • Kptlt. Klaus Popp
  • 9 September 1942 – 10 July 1944
  • Oblt.z.S. Günther Lube
  • 11 July 1944 – February 1945
  • 15 patrols:
  • 1st patrol:
  • 18 February – 16 March 1941
  • 2nd patrol:
  • 7 April – 6 May 1941
  • 3rd patrol:
  • 25 May – 2 July 1941
  • 4th patrol:
  • 18 – 26 August 1941
  • 5th patrol:
  • 4 September – 5 October 1941
  • 6th patrol:
  • 25 October – 26 November 1941
  • 7th patrol:
  • 25 December 1941 – 27 January 1942
  • 8th patrol:
  • 7 March – 27 April 1942
  • 9th patrol:
  • 9 – 19 June 1942
  • 10th patrol:
  • 4 July – 13 August 1942
  • 11th patrol:
  • 10 September – 15 December 1942
  • 12th patrol:
  • 4 April – 13 June 1943
  • 13th patrol:
  • 3 October – 30 November 1943
  • 14th patrol:
  • 8 – 14 February 1944
  • 15th patrol:
  • 16 February – 28 April 1944
  • 30 merchant ships sunk
    (163,756 GRT)
  • 1 warship sunk
    (1,190 tons)
  • 1 auxiliary warship sunk
    (520 GRT)
  • 3 merchant ships damaged
    (26,910 GRT)

German submarine U-552 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 1 December 1939 at Blohm & Voss in Hamburg as yard number 528, launched on 14 September 1940 and went into service on 4 December 1940. U-552 was nicknamed the Roter Teufel ("Red Devil") after its mascot of a grinning devil which was painted on the conning tower. She was one of the more successful of her class, operating for over three years of continual service and sinking or damaging 35 Allied ships with 164,276 GRT and 1,190 tons sunk and 26,910 GRT damaged. She was a member of 21 wolf packs.

U-552 was involved in two controversial actions: On 31 October 1941 she sank the USS Reuben James, the first US Navy warship to be lost in World War II; this was at a time when the US was still officially neutral, and caused a diplomatic row. On 3 April 1942 she sank the freighter David H. Atwater off the US seaboard.

U-552 had an unusually long service life, surviving to the end of World War II; after evacuating from her French base during the spring of 1944 she operated on training duties in the Baltic Sea until she was decommissioned in February 1945. On 5 May 1945, she was scuttled in Helgoland Bight, to prevent her falling into enemy hands.


German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-552 had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged.[1] She had a total length of 67.10 m (220 ft 2 in), a pressure hull length of 50.50 m (165 ft 8 in), a beam of 6.20 m (20 ft 4 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.74 m (15 ft 7 in). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2,800 to 3,200 metric horsepower (2,060 to 2,350 kW; 2,760 to 3,160 shp) for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 double-acting electric motors producing a total of 750 metric horsepower (550 kW; 740 shp) for use while submerged. She had two shafts and two 1.23 m (4 ft) propellers. The boat was capable of operating at depths of up to 230 metres (750 ft).[1]

The submarine had a maximum surface speed of 17.7 knots (32.8 km/h; 20.4 mph) and a maximum submerged speed of 7.6 knots (14.1 km/h; 8.7 mph).[1] When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph). U-552 was fitted with five 53.3 cm (21 in) torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm (3.46 in) SK C/35 naval gun, 220 rounds, and a 2 cm (0.79 in) C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.[1]

Service history

Initial voyage to Helgoland

Following construction, which was completed on 4 December 1940, U-552 was given two months of working-up training, during which she prepared her crew and equipment for the operations ahead. She then sailed from Kiel on 13 February to Helgoland for her first official patrol, arriving there on 18 February 1941. This port city was to remain U-552's home base until she was transferred to the occupied French port of St Nazaire in mid-March 1941.[2]

First patrol

U-552's first official war patrol began on 18 February 1941 when she left Helgoland for a patrol in the North Sea and the North Atlantic south of Iceland.[3] This first operation yielded one British tanker and one Icelandic trawler carrying fish.[4] The British tanker, Cadillac, was sunk just north of Scotland on 1 March while the trawler was sunk just south of Iceland on 10 March.[4] Following these victories, U-552 headed back to St Nazaire. The remainder of her later patrols were all conducted from the French city, which gave her easy access to the Atlantic Ocean and allowed her more time at sea.[3]

Second patrol

U-552 began her second war patrol on 7 April 1941 when she left her new home port of St Nazaire for the North Atlantic. The U-552 arrived in her assigned patrol area south-west of Iceland on 11 April.[5] No targets were engaged until 26 April when at 18:09 GMT, the U-552 was midway between Iceland and northern Scotland. Topp sighted “smoke cloud bearing 10°T” from a small “patrol vessel size” target. The target was followed “at the limit of visibility” while waiting for nightfall. At 00:10 (27 April), about 130 nautical miles SE of Iceland the small vessel Commander Horton was attacked. The U-552 log records “Fishing trawler (patrol vessel) sunk with 82 shots of 8.8 cm and 102 shots MG C30.  No resistance.” (Commander Horton, 227 tones, 14 casualties).

At about 11:00 GMT on 27 April the U-552 was submerged and “Propeller sounds heard bearing 200°T”. Topp then commenced a surface pursuit of a large steamer. “Estimate enemy speed 16 knots.  Am gaining only as a result of the zig zags.” At 14:12, at grid position AL3236, the Beacon Grange was in the targeting range of 1000 meters. The submerged U-552 fired a fan of three torpedoes. All three torpedoes hit the ship. A few minutes later while the crew were launching lifeboats, the U-552 surfaced and “ran in for a coup de grace”.  A fourth torpedo was fired and the U-boat log records “Hit aft 20 meters.Steamer breaks completely in the center, deck awash, ends continue to float.” (Beacon Grange, 10,119 tones, 2 casualties)

During the afternoon of 28 April 1941, an historic battle was underway about 180 miles south of Iceland. A wolf pack “Rudeltaktik” of five U-boats had launched the war's first submerged daylight attack on a convoy. The submerged U-boats, which were spread out over a distance of about 10 miles, intercepted and attacked an east bound convoy. The U-123 (Karl-Heinz Moehle), had spotted Convoy HX-121 and called in U-65 (Joachim Hoppe), U-95 (Gerd Schreiber), U-96 (Heinrich Lehmann-Willenbrock) and U-552 (Erich Topp) for the kill. U-552 started things off at 14:15 GMT (60°06’N 20°18’W) when it torpedoed the British tanker Capulet. There were 9 casualties and the tanker was abandoned but did not sink. At 17:25 three more ships were sunk by U-96 with one spread of three torpedoes: British tanker Oilfield (47 casualties, 8 survivors); Norwegian tanker Caledonia (12 casualties, 25 survivors); and British freighter Port Hardy (one casualty). U-65 was sunk by H.M.S. Douglas in a depth charge attack, and all 50 men in the crew perished.

After torpedoing the tanker Capulet, U-552 was depth charged in five separate attacks from destroyers H.M.S. Maori and H.M.S. Inglefield, forcing the submarine to remain submerged for hours until the convoy was out of range. The U-552 had been damaged and this would be a troubled day, with attacks from air and sea as it neared the convoy, swift dives, and gingerly resurfacing. After diving and hearing nothing at 01:45 on the 30th, Erich Topp realized that Convoy HX-121 must have changed course to the north. His convoy pursuit was broken off and his boat came to a southerly course. At 02:18 GMT, Topp sent a message to B.d.U. (Admiral Dönitz): “Sank: “Beacon Grange”, a patrol vessel. From convoy tanker 8000 tons. Return Transit via North Channel. [My position] AM2477.” In his log, Topp recorded “Intention: As long as fuel allows, position in North Channel.”

On 30 April, the surfaced U-552 was about 150 nautical miles west of the North Channel entrance … and searching for targets. At 21:40 GMT, Topp sighted a ship, the troopship S.S. Nerissa approaching from the north-west. For almost 2 hours, Topp stalked the zigzagging Nerissa and adjusted his torpedo firing solution accordingly. Finally, Topp saw a phosphorescent glow on the sea and decided that 1,000 metres was as close as he should approach his target, and he fired a fan of three torpedoes. The U-552 log records that one of the three torpedoes “hit astern” at 00:27 Berlin Time (GMT+2). About 6 minutes later, Topp closed in on the already stricken ship and fired a fourth torpedo as a coup de grace into Nerissa's aft starboard side while her crew and passengers were launching lifeboats. More than half of the 207 casualties were Canadians. (S.S. Nerissa, 5,583 tones, Casualties 207)  

The U-552 had 4 remaining torpedoes and she continued searching for merchant ships in transit towards the North Channel. Topp was not successful in engaging any additional targets and almost 48 hours after sinking the S.S. Nerissa, the U-552 commenced her homeward transit south. She arrived in St Nazaire on 6 May.[6]  [7][8]

Third patrol

U-552 left St Nazaire for her third war patrol on 25 May 1941. In 39 days, she travelled into the North Atlantic and sank three British vessels: the Ainderby on 10 June, the Chinese Prince on 12 June and the Norfolk on 18 June. During the attack on the Norfolk, U-552 attempted to attack the remaining ships in the convoy but was forced to break off the attack due to the arrival of several of the convoy's escorts. All of these attacks occurred off the northwest coast of Ireland, and once U-552 returned to St. Nazaire on 2 July 1941 she had amassed a total of 24,401 GRT from the ships she had sunk.[9]

Fourth patrol

U-552's fourth patrol was much less successful than her previous three. Having left St Nazaire on 18 August, she proceeded to head south into the waters off Portugal and Spain. It was here that she sank the Norwegian vessel, Spind. Following this sinking, U-552 returned to St Nazaire on 26 August 1941, after only nine days at sea.[10]

Fifth and sixth patrols

Her next two patrols all took her further into the Atlantic, where the danger was lessened, but so were the targets, with the result that she only hit three more cargo ships. This was also the time, during her final patrol of 1941, that she sank the Reuben James, which was torpedoed on 30 October in controversial circumstances.[11][12]

Sinking of USS Reuben James

Main article: USS Reuben James (DD-245)

On 31 October 1941, USS Reuben James was one of five destroyers escorting convoy HX-156, close to the coast of Iceland, about 600 nmi (1,100 km; 690 mi) west of the island. Reuben James had just begun turning to investigate a strong direction-finder bearing when a torpedo launched from U-552 struck her port side and caused an explosion in her forward magazine.[12] The entire bow section of the destroyer was blown off as far back as the fourth funnel and sank immediately. The stern remained afloat for around five minutes before sinking; unsecured depth charges compounded the damage, exploding as they sank and killing survivors in the water. One hundred and fifteen of her 160-man crew were killed, including all the officers.[13][14]

The destroyer was the first US Navy warship to be sunk in World War II.[12]

The incident provoked a furious outburst in the United States, especially when Germany refused to apologize, instead countering that the destroyer was operating in what Germany considered to be a war zone and had suffered the consequences. The sinking of the Reuben James did not lead the US to declare war on Germany; it did, however, provide a pretext to officially transfer the US Coast Guard from its peacetime role as an arm of the US Treasury Department to a wartime function as part of the US Navy. Congress also amended the Neutrality Act to permit the arming of US-registered merchant ships and authorized them to enter European waters for the first time since 1939.[15][16]

Second Happy Time

In 1942, again commanded by Erich Topp (who would later become an admiral in the post-war Bundesmarine), U-552 participated in the "Second Happy Time" (Operation Drumbeat or Paukenschlag), during which German submarines had great success against unescorted American merchantmen sailing alone along the eastern seaboard of the US. U-552 was particularly successful during this period, sinking 13 ships and damaging another in just three patrols in the first six months of 1942. Two further patrols under Topp during the summer netted four more ships. However, in an attack against Convoy ON-155 on 3 August 1942, the boat was nearly sunk when she was caught on the surface by the Canadian corvette HMCS Sackville. The corvette machine-gunned the submarine and hit the conning tower with a four-inch shell, causing severe damage and forcing Topp to return to base for repairs.[17] U-552 was badly damaged by heavy seas during another patrol and was put into port for repairs, during which Topp was promoted and replaced by a more cautious commander, Klaus Popp.

Sinking of the David H. Atwater

The destruction of the SS David H. Atwater, in the Atlantic Ocean 10 nmi (19 km; 12 mi) off Chincoteague, Virginia, was one of the more controversial actions of the Kriegsmarine during the Second World War, primarily due to the manner of the sinking.[18]

On the night of 2 April 1942, at the height of the U-boat offensive against US shipping known as the "Second Happy Time," the unarmed coastal steamer David H. Atwater was en route from Norfolk, Virginia to Fall River, Massachusetts,[19] with a full load of 4,000 tons of coal.

Around 21:00, between Cape Charles and Cape Henlopen,[20] the ship was ambushed by U-552, which had followed her submerged. The submarine surfaced about 600 yd (550 m) from the freighter and opened fire with her 88mm deck gun and machine guns without warning, one of her first shells destroying the bridge and killing all of the officers. In all, 93 rounds were fired from the deck gun, with 50 hits being recorded on the small freighter,[21] which rapidly began to sink.

As it did so, Topp directed his crewmen to continue firing, striking the Atwater's crewmen as they tried to man the lifeboats.[22] When Captain Webster was hit, the crew abandoned attempts to launch the lifeboats and leapt into the sea.[23]

The first ship to arrive on the scene was the small Coast Guard Patrol Boat USS CG-218, which found a lifeboat holding three survivors and three bodies; the survivors reported that they had dived overboard and swum to the boat. Next on the scene was the Coast Guard cutter USCGC Legare, which had heard the gunfire and arrived just fifteen minutes later. The Legare found a second lifeboat with a body aboard; the boat was discovered to have been riddled by gunfire, and lent strength to the widespread belief at the time that U-boats were deliberately murdering the survivors of ships they had sunk.[23] The Legare landed the three survivors and four bodies at Chincoteague Island Coastguard Station, then returned to sea to search further.[24]

The destroyers USS Noa and Herbert were directed to the scene at 21:22 and arrived at 24:00,[24] but U-552 had by then escaped the scene, going on to sink other vessels.[25]

Whether the attack on the liferafts was deliberate, or an unfortunate and unintended consequence of a nighttime attack has been heavily debated. Some of the crew of U-552 survived the war, and her captain, Erich Topp, later became an Admiral in the post-war Bundesmarine. No charges were brought against Topp, as happened to Helmuth von Ruckteschell, captain of the raider Widder for a similar offence.

Later patrols

U-552 had less success in later years, as did the U-boat force in general, as U-boats failed to keep ahead of the rapidly increasing numbers and capabilities of Allied anti-submarine efforts. She was transferred to operations off the Spanish, Portuguese and African coasts, which were nearer to base and less dangerous than the newly reorganized defenses of the United States, where she attempted to sink troopships during Operation Torch. Whilst on this duty, Topp sank a small British minesweeper and later a cargo ship, but failed to enter the Straits of Gibraltar or seriously threaten the landings.

During 1943, U-552 was increasingly unable to serve effectively against the well-prepared and organized Allied convoy system, a fact reflected by her failure to sink a single ship during her two patrols into the North Atlantic Ocean. During one of these, a Royal Air Force B-24 Liberator aircraft spotted her and she was seriously damaged by depth charges, which necessitated four months' repairs.

In 1944 she had a single patrol, but was unable to close with or threaten any Allied convoys, and so was withdrawn to Germany in April 1944 for use as a training vessel in the 22nd U-boat Flotilla, a role she fulfilled until she was decommissioned in February 1945. On 5 May 1945, she was scuttled in Wilhelmshaven bay to prevent her capture.


U-552 took part in 21 wolfpacks, namely:

Summary of raiding history

Date Ship Name Nationality Tonnage[Note 1] Fate[26]
1 March 1941 Cadillac  United Kingdom 12,062 Sunk
10 March 1941 Reykjaborg  Iceland 687 Sunk
27 April 1941 Commander Horton  United Kingdom 227 Sunk
27 April 1941 Beacon Grange  United Kingdom 10,119 Sunk
28 April 1941 Capulet  United Kingdom 8,190 Damaged
1 May 1941 Nerissa  United Kingdom 5,583 Sunk
10 June 1941 Ainderby  United Kingdom 4,860 Sunk
12 June 1941 Chinese Prince  United Kingdom 8,593 Sunk
18 June 1941 Norfolk  United Kingdom 10,948 Sunk
23 August 1941 Spind  Norway 2,129 Sunk
20 September 1941 T.J. Williams  United Kingdom 8,212 Sunk
20 September 1941 Pink Star  Panama 4,150 Sunk
20 September 1941 Barbaro  Norway 6,325 Sunk
30 October 1941 USS Reuben James  United States Navy 1,190 Sunk
15 January 1942 Dayrose  United Kingdom 4,113 Sunk
18 January 1942 Frances Salman  United States 2,609 Sunk
20 January 1942 Maro  Greece 3,838 Sunk
25 March 1942 Ocana  Netherlands 6,256 Sunk
3 April 1942 David H. Atwater  United States 2,438 Sunk
4 April 1942 Byron D. Benson  United States 7,953 Sunk
7 April 1942 British Splendour  United Kingdom 7,138 Sunk
7 April 1942 Lancing  Norway 7,866 Sunk
9 April 1942 Atlas  United States 7,137 Sunk
10 April 1942 Tarnaulipas  United States 6,943 Sunk
15 June 1942 City of Oxford  United Kingdom 2,759 Sunk
15 June 1942 Etrib  United Kingdom 1,943 Sunk
15 June 1942 Pelayo  United Kingdom 1,346 Sunk
15 June 1942 Slemdal  Norway 7,374 Sunk
15 June 1942 Thurso  United Kingdom 2,436 Sunk
25 July 1942 British Merit  United Kingdom 8,093 Damaged
25 July 1942 Broompark  United Kingdom 5,136 Sunk[27]
3 August 1942 G.S. Walden  United Kingdom 10,627 Damaged
3 August 1942 Lochatrine  United Kingdom 9,419 Sunk
19 September 1942 HMS Alouette  Royal Navy 520 Sunk
3 December 1942 Wallsend  United Kingdom 3,157 Sunk



  1. ^ Merchant ship tonnages are in gross register tons. Military vessels are listed by tons displacement.


  1. ^ a b c d Gröner 1991, pp. 43–46.
  2. ^ Helgason, Guðmundur. "Patrol info for U-552 (Initial voyage)". German U-boats of WWII - uboat.net. Retrieved 15 May 2010.
  3. ^ a b Helgason, Guðmundur. "Patrol info for U-552 (First patrol)". German U-boats of WWII - uboat.net. Retrieved 15 May 2010.
  4. ^ a b Helgason, Guðmundur. "Reykjaborg (Steam trawler)". German U-boats of WWII - uboat.net. Retrieved 15 May 2010.
  5. ^ Hessler, Gunter (1989). The U-Boat War in the Atlantic. HMSO Publications UK. pp. Diagram 10. ISBN 0117726036.
  6. ^ Dziadyk, William (2019). S.S. Nerissa, the Final Crossing. pp. ch 4, 6 and 8. ISBN 9781704113821.
  7. ^ "U-boat Kriegstagebücher (KTB) logs". U-boat Archive.
  8. ^ Helgason, Guðmundur. "Patrol info for U-552 (Second patrol)". German U-boats of WWII - uboat.net. Retrieved 15 May 2010.
  9. ^ Helgason, Guðmundur. "Patrol info for U-552 (Third patrol)". German U-boats of WWII - uboat.net. Retrieved 15 May 2010.
  10. ^ Helgason, Guðmundur. "Patrol info for U-552 (Fourth patrol)". German U-boats of WWII - uboat.net. Retrieved 16 May 2010.
  11. ^ Helgason, Guðmundur. "Patrol info for U-552 (Fifth patrol)". German U-boats of WWII - uboat.net. Retrieved 16 May 2010.
  12. ^ a b c Helgason, Guðmundur. "Patrol info for U-552 (Sixth patrol)". German U-boats of WWII - uboat.net. Retrieved 16 May 2010.
  13. ^ Morison, Samuel Eliot (2001). History of United States Naval Operations in World War II. University of Illinois Press. p. 94. ISBN 0-252-06963-3.
  14. ^ Gannon, Michael - Operation Drumbeat - the dramatic true story of Germany's first U-boat attacks along the American coast in World War II, 1990, Harper and Row publishers, ISBN 0-06-016155-8, p. 91.
  15. ^ Sweetman, Jack (2002). American Naval History: An Illustrated Chronology of the U.S. Navy and Marine Corps, 1775-present. Naval Institute Press. pp. 144. ISBN 1-55750-867-4.
  16. ^ Malsberger, John William (2000). From Obstruction to Moderation: The Transformation of Senate Conservatism, 1938-1952. Susquehanna University Press. p. 80. ISBN 1-57591-026-8.
  17. ^ W.A.B. Douglas, No Higher Purpose: The Official Operational History of the Royal Canadian Navy in the Second World War, 1939-1943, Vanwell Publishing (2004), pp. 501-502
  18. ^ Bridgland p 216
  19. ^ Browning, Robert M.; Robert M. Browning Jr. (1996). U.S. Merchant Vessel War Casualties of World War II. Naval Institute Press. p. 133. ISBN 1-55750-087-8.
  20. ^ Roscoe, Theodore (1953). United States Destroyer Operations in World War II. United States Naval Institute. pp. 73. ISBN 9780870217265.
  21. ^ Helgason, Guðmundur. "Allied Ships hit by U-boats - David H. Atwater". German U-boats of WWII - uboat.net. Retrieved 16 October 2008.
  22. ^ Herbert, Brian (2005). The Forgotten Heroes: The Heroic Story of the United States Merchant Marine. Tom Doherty Associates. p. 55. ISBN 0-7653-0707-3. "The crew was not given any chance to abandon ship, and when they tried to do so, their lifeboats were riddled by machine gun fire."
  23. ^ a b Hickam, Homer H. (1996). Torpedo Junction: U-Boat War Off America's East Coast, 1942. Naval Institute Press. pp. 122–123. ISBN 1-55750-362-1.
  24. ^ a b "Eastern Sea Frontier - April 1942 - Appendix VIII". U-boat Archive. Archived from the original on 23 August 2012.
  25. ^ Cressman, Robert (2000). The Official Chronology of the U.S. Navy in World War II. Naval Institute Press. pp. 85. ISBN 1-55750-149-1.
  26. ^ Helgason, Guðmundur. "Ships hit by U-552". German U-boats of WWII - uboat.net. Retrieved 30 January 2014.
  27. ^ Danger UXB p. 68


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