German submarine U-129 was a Type IXC U-boat of Nazi Germany's Kriegsmarine during World War II. It was laid down at the AG Weser yard, Bremen as yard number 992 on 30 July 1940, launched on 28 February 1941 and was commissioned on 21 May with Kapitänleutnant Nicolai Clausen in command.
Its service life began with training in the 4th U-boat Flotilla; she moved to the 2nd Flotilla for operations on 1 July 1941.
It sank 29 ships, a total of , on ten patrols.
German Type IXC submarines were slightly larger than the original Type IXBs. U-129 had a displacement of when at the surface and while submerged. The U-boat had a total length of , a pressure hull length of , a beam of , a height of , and a draught of . The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of for use while submerged. She had two shafts and two propellers. The boat was capable of operating at depths of up to .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . U-129 was fitted with six torpedo tubes (four fitted at the bow and two at the stern), 22 torpedoes, one SK C/32 naval gun, 180 rounds, and a SK C/30 as well as a C/30 anti-aircraft gun. The boat had a complement of forty-eight.
It made the short journey from Kiel, arriving in Horten Naval Base in Norway on 24 July 1941.
The boat's first patrol involved her departure from Horten, crossing the North Sea and entering the Atlantic Ocean by passing close to the Faroe Islands on the Icelandic side. It arrived at Lorient (where she would be based for most of her career), in occupied France on 30 August 1941.
Its second sortie saw its cross the Bay of Biscay to a point north of the Azores.
Its third patrol was further south, as far south as a similar latitude to Rio de Janeiro, but success continued to elude it.
Things improved dramatically when as part of Operation Drumbeat, it attacked Nordvangen on 20 February; this ship sank in one minute northeast of Trinidad. Staying in the West Indies / northern South America region, it sank another six vessels.
1926 D/S Cadmus (UKJ101192601) Torpedoed and sunk 01/07 by the German submarine U 129 (Kapitänleutnant Hans Ludwig Witt) in position 22.50N-92.30W while on a voyage from Tela, Honduras to Galveston, TX, USA with bananas. Two men lost. Captain Alfred Stenersen and the survivors abandoned into 2 life boats. They landed 06/07 about 60 nm south of Texpan, Mexico.
1927 MS GUNDERSEN (UKJ101192702) Departed Tela, Honduras 29/06 with 16.255 banana stems for Galveston, TX, USA. Torpedoed 01/07 by the German submarine U-129 (Kapitänleutnant Hans-Ludwig Witt) in position 23.33N-92.35V in the Gulf of Mexico. 22 were saved by Norwegian SS DEA, but an English messboy died, probably during the explosion. GUNDERSEN caught fire and sank within the next 45 minutes.
The submarine returned to its sunshine haunts; included in the toll was Hardwicke Grange, which was sunk with torpedoes and the deck gun north of Puerto Rico on 12 June 1942. It also sank Millinocket on 17 June off La Isabela, Cuba and a ship from the Soviet Union, Tuapse, in the Gulf of Mexico on 4 July.
Its sixth patrol included the sinking of Trafalgar about northeast of Guadeloupe on 16 October 1942 and West Kebar some northeast of Barbados.
Patrol number seven saw ships such as the and Panam consigned to the deep. On the return journey U129 was refuelling from the 'milk cow' supply submarine when two men were swept overboard. One was recovered fairly swiftly but the other could not be found. Her eighth patrol was west of the Canary Islands and produced no results.
U-129s ninth patrol was divided into two; she departed Lorient on 9 October 1943, but put into Saint-Nazaire on the 11th. A day later she headed for the US east coast, sinking Libertad on 4 December off North Carolina.
The boat began her last operation which at 111 days, was her longest, on 22 March 1944. Steaming south, she encountered Anadyr about south southeast of Recife in Brazil and sank her.
The boat was taken out of service at Lorient 4 July 1944; she was scuttled on 18 August. She was raised and broken up in 1946.