"In 1919," Rear Admiral F. A. Daubin reflected in 1957, "Diesel engine designing and production in our country was in swaddling clothes, barely creeping. Trucks, power plants, and railroads equipped with Diesels were not even a dream, and our Diesel-powered submarines were not sufficiently trustworthy to go to sea without the services of a nearby tender." At that time, Daubin was the assistant to the captain in charge of the submarine section of the Chief of Naval Operations. He suggested to his commander that “the Germans had good engines in their submarines. They cruised all over the Atlantic. Let’s get some of those surrendered subs at Harwich, England, take them apart and learn the secrets of the magnificent job they did for the Kaiser.”
A few phone calls later and Daubin found himself heading to England on board the submarine tender USS Bushnell (AS-2) to examine what was left of the captured German U-boat fleet after the British, French, and Japanese had already taken their picks. After a good deal of negotiating, Daubin secured U-111, and the crew set about repairing German sabotage efforts to make ready to go to New York.
By the time the now USS U-111 was ready to sail, the Bushnell, with several other German submarines in tow, had already departed for the Azores, and so Daubin powered up his submarine and made for the East Coast unescorted.
The trip was not uneventful, with breakdowns and fuel being of constant concern, though it was not without its humorous moments too. "On April 16, far to the southward," Daubin recalled, "we sighted a merchant ship headed eastward. This ship undoubtedly had taken departure from Nantucket Shoals Light Vessel—our point to change course for New York. We signalled the ship. She didn’t answer, but she must have seen us, for with a belch of smoke she turned south at full speed and began zig-zagging, taking no chances on a German submarine."
But after trial and tribulations—and a lucky signal homed in with a radio direction-finder—they steered their way to New York. "As we passed outbound ships in the channel, the crew in ranks on deck, were thrilled as each ship not only dipped their colors, but gave the U-111 a whistle salute."
U-111 proved to be a windfall for U.S. submarine technology. "The bridge, hull, periscopes, guns, torpedo tubes, machinery, and compartment design of the U-111 were far superior to the design and machinery of our submarines at that time," Daubin continued. "This was to be expected, since Germany had waged such an intensive submarine warfare, and her best ship designers and technicians had contributed. The Washington Disarmament Conference, 1921, refused to outlaw submarines, and later when our Navy began to build submarines, many of the features of the U-111 were incorporated in the new designs."
After being used for testing, U-111 was gradually dismantled to glean the secrets of her impressive construction. Daubin saw her again months later, only now she was "a rusty, abandoned hulk. The periscopes engines, motor generators, air compressors, low pressure blowers, gyro—everything had been removed, and taken to shops for dissembling and the drawing boards. Truly, the U-111 had atoned for her war sins by giving us the secrets of her reliable machinery. Nothing but a hulk remained, and it was to be sealed and towed to sea for a bombing target. In that hulk, however, must have remained some of her old spirit, for after being towed to sea, she cheated the bombers by sinking during the night."