|Ordered:||9 October 1939|
|Laid down:||12 March 1941|
|Launched:||11 December 1941|
|Commissioned:||12 February 1942|
|Fate:||Sunk 15 October 1942 in the North Atlantic in position Coordinates: , she was rammed and thereafter sunk by gun fire and a heavy depth charge by HMS Viscount.|
|Class and type:||Type VIIC submarine|
|Draught:||4.74 m (15 ft 7 in)|
|Complement:||4 officers, 40–56 enlisted|
|Operations:||5 September – 15 October 1942|
|Victories:||1 merchant ship sunk (3,672 GRT)|
German submarine U-661 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 12 March 1941 by Howaldtswerke, Hamburg as yard number 810, launched on 11 December 1941 and commissioned on 12 February 1942 under Oberleutnant zur See Erich von Lilienfeld.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-661 had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged. 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 Siemens-Schuckert GU 343/38-8 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).
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). 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-661 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.
The boat's career began with training at 5th U-boat Flotilla on 12 February 1942, followed by active service on 1 October 1942 as part of the 3rd Flotilla for the remainder of her very short career. In one patrol she sank one merchant ship, for a total of 3,672 gross register tons (GRT).
U-661 took part in three wolfpacks, namely
- Pfeil (12–22 September 1942)
- Blitz (22–26 September 1942)
- Wotan (12–15 October 1942)
U-661 was sunk on 15 October 1942 in the North Atlantic in position , she was rammed and thereafter sunk by gun fire and a heavy depth charge from Royal Navy destroyer HMS Viscount. All hands were lost.
Summary of raiding history
|14 October 1942||Nikolina Matkovic||Kingdom of Yugoslavia||3,672||Sunk|
- Helgason, Guðmundur. "The Type VIIC boat U-661". German U-boats of WWII - uboat.net. Retrieved 4 September 2014.
- Gröner 1991, pp. 43-46.
- Helgason, Guðmundur. "Ships hit by U-661". German U-boats of WWII - uboat.net. Retrieved 4 September 2014.
- Busch, Rainer; Röll, Hans-Joachim (1999). German U-boat commanders of World War II : a biographical dictionary. Translated by Brooks, Geoffrey. London, Annapolis, Md: Greenhill Books, Naval Institute Press. ISBN 1-55750-186-6.
- Busch, Rainer; Röll, Hans-Joachim (1999). Deutsche U-Boot-Verluste von September 1939 bis Mai 1945 [German U-boat losses from September 1939 to May 1945]. Der U-Boot-Krieg (in German). IV. Hamburg, Berlin, Bonn: Mittler. ISBN 3-8132-0514-2.
- Gröner, Erich; Jung, Dieter; Maass, Martin (1991). U-boats and Mine Warfare Vessels. German Warships 1815–1945. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.
- Sharpe, Peter (1998). U-Boat Fact File. Great Britain: Midland Publishing. ISBN 1-85780-072-9.
- Helgason, Guðmundur. "The Type VIIC boat U-661". German U-boats of WWII - uboat.net. Retrieved 29 December 2014.