German submarine U-753

German submarine U-753 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. Commissioned on 18 June 1941, she served with 3rd U-boat Flotilla until 30 November as a training boat, and as a front boat until 13 May 1943 under the command of Fregattenkapitän Alfred Manhardt von Mannstein.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-753 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 Garbe, Lahmeyer & Co. RP 137/c 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-753 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 a 2 cm C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history
On her sixty-five-day fourth Patrol, U-753 sank two vessels and damaging a further two in the West Indies. Her first victim was twenty-eight days into her voyage, an American merchant vessel, the George Calvert on 20 May 1942. George Calvert was destroyed by three torpedoes off the coast of Cuba, killing three of her fifty-one man crew.

Two days later, E.P. Theriault, a British sailing ship, was attacked by U-753. She did not sink, however, and was taken back to Cuba and repaired. On the morning of 25 May, the Norwegian tanker Haakon Hauan was hit by one of U-753's torpedoes. This vessel also survived and was repaired. The Norwegian tanker Hamlet, however, did not escape when she encountered the U-boat two days later. Three torpedoes were fired between eleven o'clock and noon. All thirty-six crewmembers survived the sinking and were rescued by nearby fishing boats.

U-753's sixth patrol had her patrolling the North Atlantic, on the European side. Twenty-five days into her forty-two-day voyage on 22 February, U-753 found the ON-166 convoy in the mid-Atlantic, her target: the Norwegian Whale ship N.T. Nielsen-Alonso. The vessel had in fact been abandoned earlier that day after an attack from GS U-92 (1942). U-753 fired two coups de grâce but only hit the ship with one of the torpedoes, failing to sink it. The submarine was forced to leave after a Corvette took notice.

Encounter with Irish Willow
On the morning of 16 March 1942, U-753 sighted a lone ship, south-west of the Rockall Bank, it was the SS Irish Willow (1918) and prepared to sink her, until they saw her neutral markings (the Irish tricolour and the word "EIRE"). At 2 pm U-753 surfaced and signaled "send master and ship's papers". As Captain Shanks was born in Belfast, and could be regarded as British, this was considered unwise. Chief Officer Henry Cullen, with four crew as oarsmen went instead. In the conning tower, he explained that his 39-year-old Captain was too elderly for the small boat. He reminded them that the next day would be Saint Patrick's Day. Tumblers of Schnapps were produced, along with a bottle of Cognac, for the crew.

Fate
U-753 set off on her seventh and final patrol on 5 May 1943. Eight days in, she was discovered 10 nmi away from convoy HX 237 by a Sunderland aircraft of No. 423 Squadron RCAF. After a twenty-minute exchange of fire with the aircraft, U-753 dove when the corvette HMCS Drumheller (K167) joined the engagement. The aircraft dropped two depth charges immediately after. An aircraft from the escort carrier HMS Biter (D97) marked the location of the submarine with smoke flares. HMS Lagan (K259) caught up to the Drumheller and the two dropped depth charges, finally sinking U-753; all 47 crewmen were lost at sea.

Wolfpacks
U-753 took part in ten wolfpacks, namely:
 * Schlei (19 – 24 January 1942)
 * Westwall (2 – 12 March 1942)
 * Luchs (27 September – 6 October 1942)
 * Panther (6 – 16 October 1942)
 * Puma (16 – 22 October 1942)
 * Natter (2 – 8 November 1942)
 * Kreuzotter (8 – 24 November 1942)
 * Hartherz (3 – 7 February 1943)
 * Ritter (11 – 26 February 1943)
 * Drossel (11 – 13 May 1943)