German submarine U-166 was a Type IXC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 6 December 1940 at the Seebeckwerft (part of Deutsche Schiff- und Maschinenbau AG, Deschimag) at Wesermünde (modern Bremerhaven) as yard number 705, launched on 1 November 1941, and commissioned on 23 March 1942 under the command of Oberleutnant zur See Hans-Günther Kuhlmann. After training with the 4th U-boat Flotilla, U-166 was transferred to the 10th U-boat Flotilla for front-line service on 1 June 1942. The U-boat sailed on only two war patrols and sank four ships totalling . She was sunk on 30 July 1942 in the Gulf of Mexico. Design German Type IXC submarines were slightly larger than the original Type IXBs. U-166 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, and 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 down 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-166 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 antiaircraft gun. The boat had a complement of 49. Service history First patrol U-166 first sailed from Kiel to Kristiansand, Norway, on 30–31 May 1942. The U-boat sailed on her first combat patrol, from Kristiansand on 1 June 1942, around the British Isles, and arrived at Lorient, France, 10 days later. Second patrol U-166 departed from Lorient on 17 June 1942, sailed across the Atlantic and into the Gulf of Mexico Fate Robert E. Lee was under escort from the United States Navy patrol craft PC-566 about south of the Mississippi River Delta when she was torpedoed by U-166 on 30 July 1942. PC-566 immediately attacked, making her approach vector outside