Just two days before D-Day, Captain Gallery's US antisubmarine Task Group 22.3 managed to force the German U-boat U-505 to the surface. In a bold move, a boarding party secured the submarine before it could be scuttled, capturing an Enigma machine and the current Kriegsmarine code books.

This remarkable operation earned Lieutenant Albert David the Medal of Honor for his leadership. However, it could have had catastrophic consequences. If the Germans had suspected that their cyphers were compromised, it might have jeopardised the Allied operation Ultra, which was already deciphering German signals. The Chief of US Naval Operations, Ernest King, was so incensed about the capture of U-505 that he threatened to fire Admiral Gallery.

Joining me to discuss this operation is Charles Lachman, author of Codename Nemo: The Hunt for a Nazi U-Boat and the Elusive Enigma Machine.

If you are interested in seeing the 1945 newsreel Now it can be told, you can find it here.

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