In 1940, Hitler's U-boats roamed the sea in "wolfpacks," and the North Atlantic had been turned into a vast, blood-soaked theater of war. Germany attemps to strangle Britain--U-boats--Bismarck--convoys--Allied counterattack.

Unleashing the sea wolves -- Raiders on the prowl -- "Happy Time" for U-boats -- Vital armadas -- Triumph of technology -- United States at sea -- Final round -- Picture essays: Battle's first victims -- Zany saga of the Zamzam -- Suicide of a marauder -- Submariner's eerie world -- Sinking of a U-boat -- Journeys into danger -- America's icy citadel -- Sea war on canvas -- Outpouring of ships.