Brief history of German submarine operations against Allied wartime shipping and Naval forces during World War II.

The fleet is built -- The weapon and the foe -- Problems of war : September 1939 to May 1940 -- Strike against the convoys -- Battle of the Atlantic begins -- The problems mount : Winter 1941 -- The battle area grows : Summer 1941 -- Operations in American waters : January to July 1942 -- The Arctic wastes : Winter and Spring 1942 -- Technical advances : Summer 1942 -- Return to the convoy routes -- Climax of the battle : March 1943 -- Victory into defeat -- Last throw against the supply lines -- The western approaches -- The last defence -- The final phase : January to May 1945.