German submarine U-635

German submarine U-635 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 3 October 1941 by Blohm & Voss, Hamburg as yard number 611, launched on 24 June 1942 and commissioned on 13 August 1942 under Oberleutnant zur See Heinz Eckelmann.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-635 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-635 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
The boat's career began with training at 5th U-boat Flotilla on 13 August 1942, followed by active service on 1 April 1943 as part of the 3rd Flotilla for the remainder of her very short service.

In one patrol she damaged two merchant ships, for a total of.

Convoy HX 231
In April 1943, U-635 joined the wolfpack Löwenherz and attacked the Eastbound convoy HX 231 bound for Liverpool from Halifax, Nova Scotia.

At 22:15 on 4 April, U-635’s torpedoes struck the lead ship of the column, the British freighter Shillong. GS U-630 delivered the coup de grâce. She took only 12 minutes to sink.

The next target was the British refrigerated ship Waroonga, whose cargo included butter and meat from New Zealand. She was hit with 2 torpedoes, but stayed afloat thanks to the integrity of her watertight bulkheads. However, it wasn't to last as she too was despatched by GS U-630 the following day.

Fate
U-635 was sunk on 5 April 1943 in the North Atlantic in position 58.33333°N, -31.86667°W, by depth charges from RAF Liberator of 120 Squadron. All hands were lost.

Wolfpacks
U-635 took part in one wolfpack, namely:
 * Löwenherz (1 – 5 April 1943)