From a top scholar of World War II, the “​fascinating”​ (John C. McManus) definitive history of Germany’s U-boat campaign that challenged British naval supremacy and brought international trade to its knees Winston Churchill once remarked that the only threat to truly frighten him was the peril of Nazi U-boats. Over the course of World War II, Germany’s submariners sank over three thousand Allied ships, nearly three-quarters of Allied shipping losses in all theaters of the war. In the process th