German submarine U-431 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II.She was laid down on 4 January 1940 by Schichau-Werke in Danzig as yard number 1472, launched on 2 February 1941 and commissioned on 5 April 1941 under Kapitänleutnant Wilhelm Dommes (Knight's Cross).
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-431 had a displacement of 769t when at the surface and 871t while submerged. She had a total length of 67.1m (220.1feet), a pressure hull length of 50.5m (165.7feet), a beam of 6.2m (20.3feet), a height of 9.6m (31.5feet), and a draught of 4.74m (15.55feet). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of NaNPS for use while surfaced, two AEG GU 460/8-276 double-acting electric motors producing a total of 750PS for use while submerged. She had two shafts and two 1.23abbr=onNaNabbr=on propellers. The boat was capable of operating at depths of up to .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . U-431 was fitted with five 53.30NaN0 torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.82NaN2 SK C/35 naval gun, 220 rounds, and a 2sp=usNaNsp=us C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
The boat's service began on 5 April 1941 for training as part of the 3rd U-boat Flotilla. Afterwards she transferred to the 29th flotilla operating in the Mediterranean on 1 January 1942. In 16 patrols she sank or damaged 11 ships in total.
She took part in one wolfpack, namely:
She was sunk on 21 October 1943 in the Mediterranean off Algiers at position 37.3833°N 35°W by depth charges dropped from a RAF Wellington bomber of 179 Squadron, operating out of Gibraltar. All hands were lost.
| Date | Ship Name | Nationality | Tonnage[1] | Fate[2] | |
|---|---|---|---|---|---|
| 2 October 1941 | Hatasu |  United Kingdom | 3,198 | Sunk | |
| 13 December 1941 | Myriel | United Kingdom | 3,560 | Damaged | |
| 29 January 1942 | HMS Sotra | 313 | Sunk | ||
| 20 May 1942 | Eocene | United Kingdom | 4,216 | Sunk | |
| 15 June 1942 | HMS LCT-119 | 450 | Damaged | ||
| 10 November 1942 | 1,920 | Sunk | |||
| 13 November 1942 | HNLMS Isaac Sweers | 1,628 | Sunk | ||
| 23 January 1943 | Alexandria |  Egypt | 100 | Sunk | |
| 25 January 1943 | Mouyassar | 47 | Sunk | ||
| 25 January 1943 | Omar el Kattab | 38 | Sunk | ||
| 26 January 1943 | Hassan | 80 | Sunk |