The German crew hurriedly scrambled overboard without destroying their codebooks or Enigma machine and, crucially, having failed to open sea-water vents to properly scuttle the U-boat. Three British sailors, Lieutenant Anthony Fasson, Able Seaman Colin Grazier and NAAFI canteen assistant Tommy Brown, then boarded the abandoned submarine. There are differing reports as to how the three British men boarded the U-boat. Some accounts say that they "swam naked" (such as that of Kahn), to U-559 but Sebag-Montefiore states that they either leapt from Petard or, in Brown's case, from a whaler, which was sinking, but slowly. They retrieved the U-boat's Enigma machine and the codebooks with all current settings for the U-boat Enigma key. Two German crew members, rescued from the sea, watched this material being loaded into Petard's whaler, but were dissuaded from interfering by an armed guard. Grazier and Fasson were inside the boat, attempting to escape, when the U-boat foundered; both were drowned.Read More
Sub pictured is U-36