Codename Nemo: The Hunt for a Nazi U-Boat and the Elusive Enigma Machine

A 2025 Audie Award® Finalist

The white-knuckled saga of a maverick captain, nine courageous sailors, and a US Navy task force who achieved the impossible on June 4, 1944—capturing Nazi submarine U-505, its crew, technology, encryption codes, and an Enigma cipher machine.

Two days before D-Day—the course of World War II was forever changed. The hunters of the Atlantic Ocean had become the hunted, and US antisubmarine Task Group 22.3 seized a Nazi U-boat, its crew, and all its secrets. Led by a nine-man boarding party and Captain Daniel Gallery, "Operation Nemo" was the first seizure of an enemy warship in battle since the War of 1812, a victory that shortened the duration of the war. But at any moment, the mission could have ended in disaster.

Charles Lachman tells this thrilling cat-and-mouse game through the eyes of the men on both sides of Operation Nemo—German U-boaters and American heroes like Lieutenant Albert David ("Mustang"), who led the boarding party that took control of U-505 and became the only sailor to be awarded the Medal of Honor in the Battle of the Atlantic. Three thousand American sailors participated in this extraordinary adventure; nine ordinary American men channeling extraordinary skill and bravery finished the job; and then—like everyone involved—breathed not a word of it until the war was over.

In Berlin, the German Kriegsmarine assumed that U-505 had been blown to bits by depth charges, with all hands lost at sea. They were unaware that the U-boat, its Enigma machine, and its Nazi coded messages were now in American hands. They were also unaware that the 59 German sailors captured on the high seas were imprisoned in a POW camp in Ruston, Louisiana, until their release in 1946.

A deeply researched, fast-paced World War II narrative for the ages, Charles Lachman's Codename Nemo traces every step of this historic pursuit on the deadly seas.