Frank Knox served as Secretary of the Navy during some of the most eventful years in U.S. naval history, his tenure coinciding with a number of dramas such as the innovative 1940 bases-for-destroyers initiative (which he conceptualized prior to entering the administration), the undeclared naval war in the Atlantic against Germany’s U-boats in 1941, the December 1941 attack on Pearl Harbor, the subsequent naval war in the Pacific, and naval landings in North Africa and Italy. Knox’s most important contribution to the war effort was his leadership in building a 1,000-ship fleet, without which the much-heralded landings and battles might never have been possible. In this comprehensive biography, Christopher D. O’Sullivan offers a portrait of the Roughrider in FDR’s cabinet.