German submarine U-110 was a Type IXB U-boat of Nazi Germany's Kriegsmarine that operated during World War II. She was captured by the Royal Navy on 9 May 1941 and provided a number of secret cipher documents to the British. U-110s capture, later given the code name "Operation Primrose", was one of the biggest secrets of the war, remaining so for seven months. President Franklin D. Roosevelt was only told of the capture by Winston Churchill in January 1942. Design German Type IXB submarines were slightly larger than the original German Type IX submarines, later designated IXA. U-110 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-110 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. Service history U-110s keel was laid down 1 February 1940 by DeSchiMAG AG Weser, of Bremen, Germany as yard number 973. She was launched on 25 August 1940 and commissioned on 21 November with Kapitänleutnant Fritz-Julius Lemp in command. The boat was part of the 2nd U-boat Flotilla from her commissioning date until her loss. Lemp commanded U-110 for her entire career. In an earlier boat (), he was responsible for the sinking of the passenger liner SS Athenia on the first day of the war. The circumstances were such that he was considered for court-martial. He continued, however, to be one of the most successful and rebellious commanders of his day. Operational career First patrol U-110 set out on her first patrol from Kiel on 9 March 1941. Her