German submarine U-166 (1941)

German submarine U-166 was a Type IXC U-boat of the Nazi German 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 'werk' 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 Gulf of Mexico.

1st 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, ten days later on 10 June.

2nd patrol
U-166 departed from Lorient on 17 June 1942, sailed across the Atlantic and into the Gulf of Mexico and is credited with the following "kills":

Fate
Robert E. Lee was under escort from the United States Navy patrol craft PC-566 approximately 45 mi south of the Mississippi River Delta when she was torpedoed by U-166. PC-566  immediately attacked the U-boat, and claimed to have sunk her with depth charges.

On 1 August 1942, a United States Coast Guard J4F-1 Widgeon amphibious aircraft, spotted a U-boat approximately 100 mi off the coast of Houma, Louisiana. The aircraft attacked, it appeared that the U-boat was hit in the attack. U-166 was reported missing in action on 30 July 1942, which coincided with the American aircraft's attack on "a U-Boat", leading to the aircraft being credited with the sinking of U-166. Both crewmen were decorated for the action.

Wreckage located in 2001
However, in 2001, when the wreck of Robert E. Lee was located, in more than 5000 ft of water, the wreck of U-166 was also located, less than two miles from where it had attacked the Robert E. Lee. Upon investigation, it was discovered that another U-boat, GS U-171, also operating in the Gulf of Mexico, had reported coming under attack from an American aircraft on 1 August 1942, with little damage. Therefore, the credit for the sinking of U-166 should have gone to PC-566. Charles "C.J." Christ from Houma, LA spent most of his life searching for U-166 and was involved in the final identification of the U-boat.

The site where U-166 lies, at 28.61667°N, -90.75°W has now been designated a war grave due to its crew of 52 being entombed there, and is protected from any future attempts to salvage it.