On SpyCast: The secret Navy and their hunt for a Nazi sub

It was an intelligence coup in World War Two that, well, really didn’t change the course of history. That’s what historian Alex Rose tells me of a bold mission to capture Nazi submarine U-505 off the coast of West Africa in June 1944.

The captain came up with the idea in Iceland a few years before. “It was a sort of a drunken night in the officers’ bar. He and a bunch of the boys just said to themselves, ‘Hey, you know what would be cool? Let’s capture a U-boat.”

So began a salt-soaked heist in the Atlantic. The crew intercepted the German sub with the help of a little-known Navy department called the Tenth Fleet. The “Secret Navy” had no ships or subs, but used intelligence to track and hunt the enemy’s submarine movements.

The Americans captured U-505 right before the Allies ran ashore on the beaches of Normandy. And unlike U-boat encounters before it, this one didn’t end in a sunken vessel and crew. Instead, the sailors boarded the sub and found more than 900 pounds of classified documents, plus two enigma machines.

Then they had to make the vessel and its crew disappear, so that the Nazis would not think to change their encryption protocols — thereby erasing the Allies’ intelligence advantage on the eve of D-Day.

“It didn’t change the course of the war,” Alex told me, drawing on long classified documents and intercepted transmissions to write his book, Phantom Fleet. It did show a shift in power between the Americans and British, he said, “but the real importance of the story, and this is why I told it, was that it’s an old fashioned, fantastic story of adventure on the high seas.”

Episode length: 33 minutes

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