For two years the German U-boats the most powerful underwater force ever assembled turned the seas of the Atlantic into a killing field. Now it was May 1943. The year the Allies struck back. The year the tide of war turned forever.In one extraordinary month using new tactics new weapons and the co-ordinated forces of a new generation of submarine hunters the Allies destroyed 41 U-boats and damaged 37 others in the North Atlantic sending the Nazi U-boat wolf pack running. Here distinguished naval historian Michael Gannon captures this 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 previously unreleased transcripts of secretly recorded U-boat POWs in conversation this is the epic story of two powerful enemies going head-to-head in a desperate naval battle and why one side emerged the victor and the other the vanquished.