German submarine U-402

German submarine U-402 was a Type VIIC U-boat built for the Nazi German Kriegsmarine for service during World War II.

She was laid down at the Danziger Werft in the city of the same name on 22 April 1940 as 'werk' 103, launched on 28 December 1940 and was commissioned on 21 May 1941, with Kapitänleutnant Freiherr Siegfried von Forstner in command.

The boat commenced her career with the 3rd U-boat Flotilla on 21 May 1941 carrying-out training before moving on to operations on 1 October 1941. U-402 carried out eight combat patrols, sinking 14 merchantmen and one warship for a total of over 70,000 GRT during the Second World War. She also damaged three other ships. The submarine was a member of 12 wolfpacks.

For his numerous successes, von Forstner received the Knight's Cross.

1st and 2nd patrols
No ships were sunk during the first patrol which lasted from 26 October to 9 December 1941. U-402 followed the Norwegian coast from Kiel before heading west towards the Atlantic. The submarine sailed into St. Nazaire in France, after 45 uneventful days.

On her second patrol, U-402 damaged the 12,000-ton troopship MV Llangibby Castle off the Bay of Biscay on 16 January 1942, but the troopship was able to make repairs in the Azores. U-402 returned to St. Nazaire on 11 February 1942.

3rd and 4th patrols
For her third sortie, U-402 headed for the US east coast, sinking a total of three ships, two of which were the 5,300 ton Soviet tanker Ashkhabad and her escort, the 1,000-ton converted yacht USS Cythera (PY-26) off Cape Hatteras on 2 May 1942. The U-boat had been unsuccessfully attacked by a US Navy PBY Catalina in mid-Atlantic on 29 April 1942.

The boat returned to the US eastern seaboard for her fourth patrol, but success eluded her. She returned to France, having been depth charged by patrol bombers off Cape Hatteras in mid-July and suffering a battery explosion. U-402 limped back to France, but this time to La Pallice, on 5 August 1942.

5th and 6th patrols
It was a different story on her fifth patrol; the boat attacked over 20,000 tons of shipping, including the torpedoing of five ships from convoy SC 107 which involved the sinking of the British 4,753 ton SS Empire Antelope on 2 November 1942 and a sister, Empire Sunrise, a few hours earlier.

She also had plenty of success when she attacked seven ships from convoy SC 118 on her sixth patrol.

7th and 8th patrols
Her seventh outing saw her sinking two ships from convoy SC 129. Retribution was swift; one of the escorts, HMS HMS Gentian depth charged and damaged the U-boat sufficiently to force her return to La Pallice on 26 May.

Her eighth and final patrol was marked with a paucity of targets and an ever increasing frequency of air attacks; one of which involved a Wellington of 612 Squadron, RAF on 8 September. U-402 was not hit, but the aircraft sustained enough damage to make a safe return to its base questionable.

Loss
U-402 had departed La Pallice on 4 September 1943. On the 13 October she was sunk by a Mark 24 FIDO Torpedo dropped by TBF Avenger aircraft from the escort carrier USS Card.