German Submarine U-559

German Submarine U-559

German submarine U-559 was a Type VIIC U-boat built for the Nazi German Kriegsmarine for service during World War II.

Laid down on 1 February 1940 at the Blohm & Voss shipyards in Hamburg as "Baunummer 535" ("Yard number 535"), she was launched on 8 January 1941 and commissioned on 27 February under Kapitänleutnant Hans Heidtmann.

She began her service career with the 1st U-boat Flotilla, undergoing training before being declared operational on 1 June 1941. She moved to the 29th U-boat Flotilla on 15 April 1942. She sank five ships but is perhaps best remembered for an incident during her sinking in the Mediterranean Sea in 1942, in which British sailors seized cryptographic material from U-559. This material was extremely valuable in breaking the U-boat Enigma cipher.