Part 3 (1992): Outlines the true history of the submarine and wartime strategies with the assistance of well-known German U-Boat commanders, their British counterparts and American veterans. As early as the Civil War, a new breed of predator appeared in the seas and in one frightening instant forever changed the balance of world power. The submarine, by pure function of design and simplicity in purpose, evolved into the most terrifying weapon of mass destruction ever seen. Obeying only the tenants of surprise and stealth, submarine warfare in both World Wars was by necessity a ruthless endeavor. Now there were only two kinds of ships: subs and targets. German U-boat wolf packs nearly strangled a nation, U.S. submarines sank 1/3 of the Japanese Navy. And Japan's suicide subs threatened to make the Pacific Fleet obsolete. Inspiring fear from the moment of their creation, no one could have predicted just how deadly these machines ultimately would prove to be.