German submarine U-645

German submarine U-645 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 17 December 1941 by Blohm & Voss, Hamburg as yard number 621, launched on 3 September 1942 and commissioned on 22 October 1942 under Leutnant zur See Otto Ferro.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-645 had a displacement of 769 t when at the surface and 871 t while submerged. She had a total length of 67.10 m, a pressure hull length of 50.50 m, a beam of 6.20 m, a height of 9.60 m, and a draught of 4.74 m. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2800 to 3200 PS for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 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 17.7 kn and a maximum submerged speed of 7.6 kn. When submerged, the boat could operate for 80 nmi at 4 kn; when surfaced, she could travel 8500 nmi at 10 kn. U-645 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 twin 2 cm C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history
This boat's career began with training at 5th U-boat Flotilla on 22 October 1942, followed by active service on 1 May 1943 as part of the 3rd Flotilla for the remainder of her service. In three patrols she sank two merchant ships, for a total of.

Wolfpacks
U-645 took part in eight wolfpacks, namely:
 * Without name (5–10 May 1943)
 * Isar (10 – 15 May 1943)
 * Donau 1 (15 – 26 May 1943)
 * Leuthen (15 – 24 September 1943)
 * Rossbach (24 September – 9 October 1943)
 * Coronel 2 (13 – 14 December 1943)
 * Coronel 3 (14 – 17 December 1943)
 * Borkum (18 – 24 December 1943)

Fate
U-645 has been missing since 12 December 1943 in the North Atlantic northwest of Spain.

Previously recorded fate
U-645 was sunk on 24 December 1943 in the North Atlantic in position 45.33333°N, -21.66667°W, by depth charges from USS Schenck (DD-159). All hands were lost.