German submarine U-623

German submarine U-623 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 15 July 1941 by Blohm & Voss, Hamburg as yard number 599, launched on 31 March 1942 and commissioned on 21 May 1942 under Oberleutnant zur See Hermann Schrüder.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-623 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-623 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 an anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history
The boat's career began with training at 8th U-boat Flotilla on 21 May 1942, followed by active service on 1 December 1942 as part of the 6th Flotilla for the remainder of her service.

In two patrols she sank no ships.

Wolfpacks
U-623 took part in five wolfpacks, namely
 * Drachen (22 November – 3 December 1942)
 * Panzer (3–9 December 1942)
 * Ungestüm (11–13 December 1942)
 * Raufbold (13–18 December 1942)
 * Ritter (11–21 February 1943)

Fate
U-623 was caught while hurrying on the surface to join the attack against Convoy ON 166 and sunk on 21 February 1943 in the North Atlantic, at the position 48.13333°N, -29.61667°W, by depth charges from a RAF Liberator of 120 Squadron. All hands were lost.