German submarine U-55 (1939)

German submarine U-55 was a Type VIIB U-boat of Nazi Germany's Kriegsmarine during World War II. She was ordered on 16 July 1937 and laid down on 2 November 1938 at Friedrich Krupp Germaniawerft in Kiel as yard number 590. Launched on 19 October 1939, she went into service on 21 November 1939 under the command of Kapitänleutnant (Kptlt.) Werner Heidel.

Design
German Type VIIB submarines were preceded by the shorter Type VIIA submarines. U-55 had a displacement of 753 t when at the surface and 857 t while submerged. She had a total length of 66.50 m, a pressure hull length of 48.80 m, a beam of 6.20 m, a height of 9.50 m, and a draught of 4.74 m. The submarine was powered by two MAN M 6 V 40/46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2800 to 3200 PS for use while surfaced, two AEG GU 460/8-276 double-acting electric motors producing a total of 750 PS for use while submerged. She had two shafts and two 1.23 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 17.9 kn and a maximum submerged speed of 8 kn. When submerged, the boat could operate for 90 nmi at 4 kn; when surfaced, she could travel 8700 nmi at 10 kn. U-55 was fitted with five 53.3 cm torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, and one 2 cm anti-aircraft gun The boat had a complement of between forty-four and sixty.

Service history
U-55 began her first and only war patrol on 16 January 1940, under Heidel's command; he had previously sunk two ships in GS U-7 (1935). She sank four small freighters sailing independently, then attacked convoy OA-80G on 29 January. U-55 sank two more ships before coming under concerted attack from the convoy's escorts, supported by a Sunderland flying boat from RAF Coastal Command 228 Squadron.

Fate
After a sustained depth charge attack, the U-boat surfaced and carried out a running gun battle before her deck gun jammed. Heidel ordered the boat to be abandoned, then apparently went down with it. The remainder of the crew was rescued by the escorts. The British awarded official credit for sinking U-55 to the sloop HMS Fowey (L15), the destroyer HMS Whitshed (D77), French destroyers Valmy and Guépard, and the Sunderland.