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U-505 Capture: How the US Navy Seized Enigma Materials
- What: U-505, a German submarine, was captured intact by the US Navy on June 4, 1944, along with code materials linked to the naval Enigma system.
- Where: In the Atlantic west of Africa.
- When: World War II, on June 4, 1944.
On June 4, 1944, in the Atlantic west of Africa, a German submarine surfaced under attack and something happened that was almost never supposed to happen in wartime: enemy sailors boarded it and took it intact. The submarine was U-505, and the US Navy crew that reached it did not just capture a boat. They seized code materials linked to Germany’s naval Enigma system.
How U-505 Was Captured
The action began when Task Group 22.3, built around the escort carrier USS Guadalcanal and commanded by Captain Daniel V. Gallery, forced U-505 to the surface. Depth charges and coordinated attacks from the American ships left the U-boat damaged and its crew abandoning ship. Normally, a submarine in that condition would sink, either from damage, flooding, or scuttling charges set by its own crew.
But a US Navy boarding party moved fast. Men from USS Pillsbury got aboard the drifting submarine while it was still taking on water. Inside, they found classified documents, codebooks, and operating materials before securing the vessel itself. American sailors then worked to keep U-505 from sinking, plugging leaks and eventually towing it away.
Enigma Materials and Secrecy
That combination is what made the capture so rare. Navies destroyed enemy ships all the time. Capturing a modern warship on the open ocean, especially a submarine carrying current cryptographic material, was something else. The strategic value was not just the steel hull. It was the paperwork, settings, and procedures that could help Allied codebreaking and anti-submarine warfare. Historians are careful here: Enigma intelligence was part of a much larger Allied effort, and U-505 was one important source among several. But intact material from a front-line U-boat mattered.
Secrecy mattered too. The US kept the capture quiet so Germany would not immediately know how much had been taken. Even many of the German prisoners were isolated to prevent the story from spreading. The goal was simple: preserve whatever intelligence advantage the seizure might provide.
Where U-505 Is Today
Today, U-505 survives far from the Atlantic. It is preserved at Chicago’s Museum of Science and Industry, where the result of that June 1944 boarding is visible in a very concrete form: not a replica, not a recovered fragment, but the actual submarine that American sailors managed to stop from vanishing beneath the water.
Did You Know?
U-505 is a captured German submarine preserved in the United States.
