This, the first of two volumes on Germany's World War II U-boats, traces their development from the early U-boats of the Kaiser's Navy, culminating in the formation of the 1st U-boat Flotilla in 1935 with the modern Type II.

Gordon Williamson explores key moments in the U-boats' history, such as the prohibition on Germany having U-boats following the Armistice in 1918 and the subsequent Treaty of Versailles, and the secret development of U-boats using a 'cover-firm' in Holland.

The operational history section includes examples from the Classes Type VIIA, Type VIIB, VIID, VIIE and VIIF before concentrating on the mainstay of the U-boat arm, the Type VIIC. Comparisons are also made with the standard allied submarines, their strengths, weaknesses and U-boat tactics.