On May 15, 1944, Task Group 22.3 sailed from Norfolk, Virginia for an antisubmarine patrol near the Cape Verde Islands. For weeks, Captain Dan Gallery and the six ships in the Task Group searched the area for a U-boat, assisted by daily location briefings transmitted from the F-21 submarine tracking room back in Washington, D.C.

The Task Group used all its technologies and determination to locate the target U-boat. Wildcat fighters from the USS Guadalcanal searched from the sky as sonar and hydrophone operators listened in the sea, but they couldn't find the U-boat. A frustrated Gallery called off the search and began to head toward Casablanca for fuel.

Then, minutes later, the sonar operator on the USS Chatelain reported a possible U-boat contact...