The largest anti-submarine operation in American history was launched to stop a weapon that didn't exist.

The Night the Kriegsmarine Lost Its Last Weapon: Operation Teardrop

When Hitler's Submarine Wolfpack Carried a Secret Terror Toward New York

America's largest submarine hunt was launched over fears Nazi U-boats carried atomic dirty bombs toward New York.

The Atlantic was black as oil on the night of September 10, 1945, when the war was already over but its ghosts still hunted. Except this story belongs to an earlier darkness—April 1945—when Nazi Germany's final desperate gamble sent six U-boats screaming toward the American coast with orders that chilled Allied intelligence to the bone.

But let us step back to September 10, 1944, when the seeds of this terror were planted. In a concrete bunker beneath Kiel, Admiral Karl Dönitz authorized Operation Seewolf—later morphed into what Americans would call 'Teardrop.' The mission: deploy the revolutionary Type XXI submarines, vessels so advanced they could reach New York Harbor without surfacing. What they might carry remained the nightmare that kept Naval Intelligence officers awake.

Intercepted Enigma transmissions spoke of 'special weapons.' V-1 rockets? Biological agents? The terrifying rumor spreading through Allied command suggested something worse: components for a radiological 'dirty bomb,' assembled from Germany's failed nuclear program. The Americans couldn't know the truth. They could only prepare for the worst.

By spring 1945, two carrier groups—the largest anti-submarine f…

💡 The FBI interrogated captured U-boat crews at sea using methods so aggressive that several crewmen later testified about mistreatment, a fact buried in classified files until the 1990s.