My first book about WW2 was a book about US sub warfare in the Pacific. Ever since, I've been particularly interested in submarine warfare. And I've accumulated at least as many books about sub warfare as I have about any other aspect of WW2. As with my books about land and sea combat, almost all my books about sub warfare divide neatly into books about the European war and the Pacific war. This is a comprehensive single-volume look at WW2 submarine warfare in both the Atlantic and Pacific.
British subs get rather limited treatment, and Japanese submarines are barely mentioned at all.
In the Atlantic, the primary submarine war was the attacks of the German U-boats against the Allied convoy lines. However, the British waged submarine warfare too, especially in the Mediterranean. In March 1943, Germany's U-boats wrought havoc in the Atlantic convoy lanes, sinking over a hundred ships and losing only a handful of their own number. For a brief time, victory in the Battle of the Atlantic seemed to be within their grasp. Black May happened.