U-559
U-boat from which codebooks and valuable cryptographic materials were recovered before sinking, facilitating, in late 1942, the second major Allied breakthrough in reading German U-boat communications. (For more on the breaking of the Enigma, see Decoding Nazi Secrets.)

Type: VII C
Built: Blohm & Voss, Hamburg
Keel laid: 1 February 1940
Launched: 8 January 1941
Commissioned: 27 February 1941
Commander: KL Hans Heidtmann
Fate: While operating in the eastern Mediterranean, U-559 came under attack by several British warships and an aircraft on 30 October 1942. Fatally damaged and forced to the surface, the sub was abandoned. A British boarding party from destroyer HMS Petard recovered the cryptographic materials, but the vessel sank before the cipher machine could be brought out. Eight German crewmen and two British seamen were lost, and 37 German survivors were taken prisoner.