For three years German U-boats turned the Atlantic Ocean into a killing field, but in May 1943, the Allies struck back successfully and reversed the tide of war. In just one month, using new tactics, new technology, and the coordinated forces of a new generation of submarine hunters, the Allies destroyed 41 U-boats and damaged 37 others. With this book, the noted naval historian Michael Gannon illuminates the epic battle and those who shaped it, from the men who made key command decisions to the sailors trapped inside the steel-hulled U-boats as they were pounded by Allied depth charges. Drawing on never-before-released transcripts of secretly recorded conversations of U-boat POWs, Gannon tells the story of two powerful enemies going head-to-head in a desperate naval battle and explains why one side emerged the victor.