U-166 sailed from Lorient, France on June 17, 1942. The war in Europe was nearly three years old, but the conflict had barely touched the waters of the Gulf of Mexico and the Caribbean. Only six months after its official entry into the war, the United States was still learning how to handle the U-boat menace and, generally speaking, wasn't doing a very good job. Many merchant ships continued sailing alone and unescorted, and some coastal cities were still reluctant to enforce blackout regulations -- after all, the blackout was bad for tourism!

Kuhlmann's first war patrol as commander started off inauspiciously, when he intercepted the 84-ton Dominican schooner Carmen off that country's northern shore on July 11. Not wanting to waste valuable torpedoes on such a small target, he attacked on the surface and sank the boat with gunfire. Two days later bigger game appeared, the 2,309-tom U.S. steam freighter Oneida, off the eastern tip of Cuba. Kuhlmann sent her to the bottom with six dead and continued west along the Cuban coast.

On the evening of July 16, 1942, about thirty miles northeast of Havana, U-166 encountered an ancient and tiny motorized fishing vessel called Gertrude. Kuhlmann may have been amused that this little boat bore the same name as his wife. The 16-ton boat was far too small for a torpedo, so he ordered the trawler's three-man crew into a motorboat and sank the trawler with gunfire. The motorboat ran out of fuel before reaching Cuba, and the crew drifted for three days before being picked up in the Florida Keys.

Kuhlmann and his crew never knew about it, but their encounter with Gertrude gained some notoriety after the trawler's crew was picked up and questioned by the U.S. Navy. Press releases, always looking for a good propaganda angle, suggested that Gertrude had been attacked and "hijacked" for food "by a Nazi U-boat crew apparently desperate for provisions." The resulting article appeared in the New York Times on July 28 and undoubtedly caused a few chuckles, especially when readers learned that the trawler's cargo consisted of twenty tons of onions.

An article from the New York Times of July 28, 1942, explaining how the trawler Gertrude had been attacked by a U-boat "desperate for provisions." Interestingly, the paper's next column (lower right) describes the sinking of the Mexican steamer Oaxaca near Freeport, Texas. That ship was sunk by U-171, which was depth-charged several days later by a Coast Guard aircraft off the Louisiana coast. Although U-171 got away, the air attack was believed for more than 50 years to have sunk U-166, until the wreck of Kuhlmann's boat was finally identified in 2001.

For the next two weeks, Kuhlmann patrolled off the Cuban coast and gradually moved northward into the northern Gulf of Mexico. By the end of the month, U-166 was off the mouth of the Mississippi River, in an excellent position both to intercept traffic coming in and out of New Orleans and also to encounter tankers steaming eastward from the Texas Gulf ports. Oberleutnant Kuhlmann was probably getting anxious for a suitable target; he hadn't come five thousand miles to sinking fishing boats. But patience paid off. On the afternoon of July 30, Kuhlmann's lookouts spotted smoke away to the southeast. It was the passenger steamer Robert E. Lee. Neither the steamer nor the submarine would survive the coming encounter.
 

Additional data from: Uboat.net