Gulf of Mexico
Once convoys and air cover were introduced in the Atlantic, sinking numbers were reduced and the U-boats shifted to attack shipping in the Gulf of Mexico. During 1942 and 1943, more than 20 U-boats operated in the Gulf of Mexico. They attacked tankers transporting oil from ports in Texas and Louisiana, successfully sinking 56 vessels. By the end of 1943, the U-boat attacks diminished as the merchant ships began to travel in armed convoys.
In one instance, the tanker Virginia was torpedoed in the mouth of the Mississippi River by the German U-Boat U-507 on May 12, 1942, killing 26 crewmen. There were 14 survivors. Again, when defensive measures were introduced, ship sinkings decreased and U-boat sinkings increased.
U-166 was the only U-boat sunk in the Gulf of Mexico during the war. Once thought to have been sunk by a torpedo dropped from a U.S. Coast Guard Utility Amphibian J4F aircraft on August 1, 1942, U-166 is now believed to have been sunk two days earlier by depth charges from the Robert E. Lee’s naval escort, the U.S. Navy sub-chaser, PC-566. It is thought that the J4F aircraft may have spotted and attacked another German submarine, U-171, which was operating in the area at the same time. U-166 lies in 5,000 feet of water within a mile of her last victim, the passenger ship SS Robert E. Lee.