German submarine U-66 was a Type IXC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 20 March 1940 at the AG Weser yard at Bremen, launched on 10 October and commissioned on 2 January 1941 under the command of Kapitänleutnant Richard Zapp as part of the 2nd U-boat Flotilla. Design German Type IXC submarines were slightly larger than the original Type IXBs. U-66 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-66 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 After her transfer from a training organization to front line service in May 1941, until her sinking in May 1944, U-66 conducted nine combat patrols, sinking 33 merchant ships, for a total of , and damaged two British motor torpedo boats. She was a member of four wolfpacks. U-66 was the seventh most successful U-boat in World War II. On 6 May 1944, during her ninth patrol, she was sunk west of the Cape Verde Islands by depth charges, ramming and gunfire from Grumman TBF Avenger and Grumman F4F Wildcat aircraft of the US escort carrier and by the destroyer escort . Patrols First On 13 May 1940, three days after the start of the invasion of France, U-66 departed her homeport of Kiel under the command of Richard Zapp, a future Knight's Cross recipient, on her first patrol. After about 10 days she rounded the northern coast of Britain and made her way into the