This 1921 Pulitzer Prize awarded history has been written in response to a demand for some account of the generally very misunderstood German submarine campaign in the World War I and particularly of the means by which it was defeated. The interest of the public in such a story is due to the fact that during the war the sea forces were compelled to take all possible precautions to keep the enemy from learning anything about the various devices and means used to oppose or destroy the under-water craft. Contents: When Germany Was Winning the War The Return of the "Mayflower" The Adoption of the Convoy American Destroyers in Action Decoying Submarines to Destruction American College Boys and Subchasers The London Flagship Submarine Against Submarine The American Mine Barrage in the North Sea German Submarines Visit the American Coast Fighting Submarines from the Air The Navy Fighting on the Land Transporting Two Million American Soldiers to France