During World War I, the American Merchant Marine meant dangerous duty. Sailors on cargo ships faced the daily threat of enemy submarines, along with the usual hazards of life at sea, and help was rarely close enough for swift rescues. Pre-war shipping in America depended mainly on foreign vessels, but with the outbreak of war these were no longer available. Construction began quickly on new ships, most of which were not completed until long after the end of the war. Drawing on contemporary newspapers, magazines and trade publications, and Shipping Board, Department of Commerce and...