Originally designed in 1934 as a small simple submarine for anti-submarine training, the U class submarine's career turned out to be far more dramatic and valuable than that. By the end of the war seventy-two U class submarines had been commissioned and of these seventeen were lost to the enemy and three in accidents. Officers and men serving on these submarines received no less than 375 gallantry medals including the Victoria cross awarded to Lt Cdr Wanklyn.

Manned by crews from seven nations' navies, they served worldwide, and never more successfully than in the Mediterranean. This book is the definitive study of this class of submarine and the men who serve on them.