U-166 took down the Robert E. Lee more than seventy years ago this month.
U-166, veteran Oberleutnant zur See Hans-Günther Kuhlmann commanding, was 44 days into its first war patrol and had sunk over 2,400 tons worth of shipping before meeting the armed passenger steamer Robert E. Lee and her escort, USS PC-566, a sub-chaser. The Robert E. Lee, at over 5,000 tons, was the largest target U-166 ever encountered, and on July 30th, 1942, Oberleutnant Kuhlmann took her down with one torpedo. She took about 15 minutes to sink, drowning one officer, nine crew and fifteen of her more than two hundred eighty passengers, but by then U-166 had troubles of its own. PC-566 busily dumped as many depth charges it could fire on the U-boat's suspected position and, though the truth wasn't to be known until decades afterward, scored. U-166 went down with all hands, taking her fifty two crewmen to the bottom of the Gulf of Mexico.
U-166 is now a war grave, and lies only two miles away from the remains of the Robert E. Lee. Most of the images you see here are of the two ships on the bottom, taken this month as part of EV Nautilus' ongoing underwater exploration program. The Nautilus is operated by the Ocean Exploration Trust, under the leadership of Titanic and Bismark finder Dr Robert Ballard. There's a video of the original 2009 discovery on YouTube, but the video owner has prevented it from being embedded, so if you want to see it go here. Two images are of the ships while they were still alive - U-166's victim and her killer - while the final image is that of Oberleutnant zur See Hans-Günther Kuhlmann.
As for USS PC-566, it became the Honesdale in 1956, and was later sold to Venezuela and renamed Calamar in 1961. The Venezuelan navy struck the Calamar off its list in 1978, and nobody knows what happened to her after that.