The next patrol into the region, beginning south of Bermuda on the 8th of July 1942, was remarkable both for its success (three Allied sinkings) and its failure south of New Orleans. The boat was sunk there, the only U-boat to leave its hull in the US Gulf during the war, and the sub was discovered by a BP drilling survey team over fifty years later. In the evening of the 8th of July U-166 under Hans-Günther Kühlmann changed its westward course (it was heading towards the Straits of Florida until then) to a 90-degree turn southwards.
U-166 steamed in that direction until the 11th, when it reached a point just north of the Mona Passage separating Puerto Rico and the Dominican Republic. Taking another sharp turn, this time to the right, it proceeded westwards up the coast of the Dominican Republic, where it encountered and sank the 84-ton Dominican schooner Carmen on the 11th. Two days later, while steaming up the Old Bahama Channel and after passing Inagua on the starboard beam, U-166 sank the 2,309-ton American freighter Oneida.
Proceeding northwest and leaving the Old Bahama for the Saint Nicholas Channel, Kühlmann came upon a small fishing boat of sixteen tons loaded with onions that shared the name of his wife – the American boat Gertrude. The survivors (a small crew of three under Walter Broward Crosland) transferred to an even smaller boat – this one a motorboat of fourteen feet, which ran out of fuel, causing them to drift for 78 hours until rescued off Alligator Reef, Florida.
U-166 left this trail of destruction for the Allies to follow, and on the 30th of July, after the boat had left the area on the 16th, it caught up with him. In a pitched battle with the 5,184 passenger ship Robert E. Lee (which carried survivors of earlier U-boat sinkings) and her escorts off New Orleans U-166 was sunk on 30 July by a US Coast Guard plane under H. C. White (Wynn, Vol. 1, p.127). The Robert E. Leewent down – as mentioned the wrecks of both ships were recently discovered and have been extensively documented with photographs and sub-sea imagery. The patrol had begun in Lorient on only its second patrol on the 17th of June 1942.
Hans-Gunther Kühlmann was only 28 years of age and an Oberleutnant zur Seewhen he was lost off the coast of Louisiana, far from his birthplace of Cologne-Sulz. In two patrols of 54 days at sea he sank a total of 7,593 tons including the small coastwise ships Carmen and Gertrude – all tonnage being those lost in the greater Bahamas region with the exception of the Robert E. Lee. He won no decorations.
SOURCES: Gudmundur Helgason, Rainer Kolbicz, www.uboat.net, 2011, Kenneth Wynn, U-boat Operations of the Second World War, Volume 1 and Volume 2, 1997, Melanie Wiggins, Torpedoes in the Gulf, 1995