German submarine U-413

U-413 was a Type VIIC U-boat built for the Nazi German Kriegsmarine for service during World War II. She was commissioned in mid 1942, with Oberleutnant zur See Gustav Poel in command. Poel commanded her (receiving promotion to Kapitänleutnant), until April 19 1944, when he was relieved by Oberleutnant Dietrich Sachse who commanded her until her loss.

U-413 was laid down on 25 April 1941 at the Danziger Werft (as 'werk' 114), launched on 15 January 1942 and commissioned on 3 June. She conducted eight patrols in World War II, sinking six ships totalling 37,985 tons.

1st and 2nd patrols
The U-boat departed Kiel on October 22 1942, on her first patrol. On November 14, 1942, she sank the 20,107-ton troop transport ship MV Warwick Castle (one of the largest sunk in World War II). At 8:44 am, the ship, under the command of Henry Richard Leepman-Shaw in convoy MKF-1X was hit by one of two torpedoes fired, about 200 miles northwest of Cape Espichel, Portugal. The U-boat hit her again at 8:57 am, causing the ship to sink about one hour later. The master, 61 crew members and 34 service personnel died. 201 crew members, 29 gunners and five naval and 131 service personnel were rescued by HMS Achates (H12), HMS Vansittart, HMCS Louisburg (K-143), and the British MV Leinster. The ship had been in Convoy KMF-1 for Operation Torch, (the invasion of North Africa). On November 19, 1942, U-413 was attacked by a British Lockheed Hudson aircraft with five bombs and was damaged so severely that she had to return to a new base - Brest in occupied France.

Her second patrol was marked by sinking the American ship West Portal in mid-Atlantic on 5 February 1943; there were no survivors. She also attacked and sank the Greek Mount Mycale on 22 February 1943, northeast of Newfoundland.

3rd and 4th patrols
Her third patrol saw her leave Brest on March 29 1943, once more for the Atlantic. There, she sank the British vessel Wanstead south of Greenland, whose survivors were picked up by the corvette HMS Poppy and the ASW (anti-submarine warfare) HMS Northern Gift.

Her fourth sortie was a frustrating one; it was split into three parts, but she failed to sink any ships.

5th and 6th patrols
On Feb 20 1944, she sank the British 1,100 ton destroyer HMS Warwick (D25) about 15 miles off Trevose Head, north Cornwall. This was Poel's last patrol. He moved to the Marineschule (naval academy) at Mürwik in Flensburg.

7th patrol and sinking
Her last victory was when she sank the Saint Enogat on August 19 1944 in the English Channel. U-413 did not suffer any casualties until August 20 1944, when she was sunk, also in the English Channel, by depth charges from the British escort destroyer HMS Wensleydale (L86) and the destroyers HMS Forester and Vidette. 45 of her crew were killed; there was one survivor.

The wreck of U-413 was located and identified by marine archaeologist Innes McCartney in 2000 close to the official sinking position.

Trivia
Neal Stephenson's novel Cryptonomicon features a fictitious U-413, a milchkuh.