German submarine U-420

German submarine U-420 was a Type VIIC U-boat built for the Kriegsmarine for service during World War II. She was laid down in the Danziger Werft as yard number 121, launched on 18 August 1942 and commissioned on 16 December the same year under Oberleutnant zur See Peter Högqvist. She then joined the 8th U-boat Flotilla for training before transferring to the 11th flotilla for operations.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-420 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 Siemens-Schuckert GU 343/38–8 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-420 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 two twin 2 cm C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.

First patrol
U-420's first patrol involved her leaving Kiel on 12 June 1943 and arriving at Lorient in occupied France on 16 June 1943, having hugged the Norwegian coast and sailed around the north of Scotland. She then crossed the Atlantic, but was attacked on 3 July by a Canadian B-24 Liberator. The boat was hit by a Fido homing torpedo which killed two men and wounded a third. The boat sustained enough damage to force the patrol to be cut short.

Second patrol and loss
Following a short transit voyage from Lorient to Brest, U-420 set off on her second patrol on 9 October 1943. After 20 October, she was never heard from again and her fate remains an unsolved mystery.

Previously recorded fate
A postwar assessment stated that U-420 was sunk on October 26, 1943 in the North Atlantic at position 50.81667°N, -41.01667°W by depth charges from a Canadian B-24 Liberator of RCAF Squadron 10/A. This attack was actually against GS U-91 (1941), inflicting no damage.