The keel for U-164 was laid down on June 20, 1940, at the Deutsche Schiff- und Maschinenbau yard in Bremen, assigned yard number 703. She was launched on May 1, 1941, and commissioned on November 28, 1941, under Korvettenkapitan Otto Fechner. The Type IXC class was designed for long Atlantic patrols rather than the faster, smaller Type VIIs that dominated the early war: 76 meters long, displacing 1,120 tons surfaced, and capable of 13,450 nautical miles at 10 knots on her diesel engines. She carried 22 torpedoes for her six tubes, a 10.5-centimeter deck gun, and anti-aircraft weapons that would prove inadequate against American patrol planes with surprise on their side. Her complement was forty-eight men, though additional personnel sometimes brought the number aboard higher.

After training with the 4th U-boat Flotilla, U-164 joined the operational 10th flotilla on August 1, 1942, and set sail from Kiel on July 18 for her first war patrol. The route took her across the North Sea and out into the Atlantic through the gap between Iceland and the Faroes. On August 25, in the eastern Caribbean, she fired on the Dutch merchant Stad Amsterdam. The first torpedoes hit but failed to detonate, probably launched from too close. A second shot sank the ship stern-first. She sank the American freighter John A. Holloway northwest of Curacao next. After nearly three months at sea, U-164 made port at Lorient in occupied France on October 7, 1942. The Atlantic base would be her only home for the rest of her career.

U-164's second and final patrol took her back into the tropical Atlantic. On January 1, 1943, she stopped the Swedish merchant Brageland, a ship from a neutral country. Under prize rules, a U-boat was supposed to inspect neutral shipping and release it if no contraband was found. Fechner sent a three-man boarding party across to the freighter. What they found or judged is lost to the historical record, but the decision taken was final: U-164 torpedoed the Brageland. The ship went down, and the sinking of a neutral merchantman drew diplomatic concern from Stockholm. It was the last ship U-164 would sink.

Five days later, the PBY Catalina of VP-83 found her. The squadron was operating from northern Brazil as part of an expanding US Navy anti-submarine presence in the South Atlantic, a theater where German boats had been preying on Allied shipping running along the Brazilian coast. The depth-charge attack killed the submarine quickly. Only two of the fifty-six men aboard survived, plucked from the water after their vessel had sunk beneath them. For those two survivors, and for the relatives of the fifty-four who did not return, the war was now a specific coordinate in the tropical Atlantic: a grave on the sea floor at roughly two degrees south and thirty-nine degrees west, far from Bremen, far from Lorient, far from anywhere home.

A submarine lost with most of its crew is easy to reduce to a statistic, especially when the war it served has been so thoroughly condemned by history. But every U-boat sailor was a person: young men, some teenagers, mechanically skilled, pressed into service by a regime many of them had not chosen and could not safely oppose. The same is true, in different ways, for the merchant seamen who died aboard Stad Amsterdam, John A. Holloway, and Brageland, civilian crews caught in a war fought around their cargoes. The tropical waters off Ceara hold the bones of ships and men from several nations. Fifty-four Germans lie with U-164 in the dark. Merchant sailors who died at her torpedoes lie scattered across different pieces of the Atlantic floor. A complete accounting of the submarine war is a long list of such names, which is why the numbers matter less than the fact that each one was someone.