The Cold War was the first major conflict between superpowers in which victory and defeat were unambiguously determined without the firing of a shot. Without the shield of a strong, silent deterrent or the intellectual sword of espionage beneath the sea, that war could not have been won. John P. Craven was a key figure in the Cold War beneath the sea. As chief scientist of the Navy's Special Projects Office, which supervised the Polaris missile system, then later as head of the Deep Submergence Systems Project (DSSP) and the Deep Submergence Rescue Vehicle programme (DSRV), both of which engaged in a variety of clandestine undersea projects, he was intimately involved with planning and executing America's submarine-based nuclear deterrence and submarine-based espionage activities during the height of the Cold War. Craven was considered so important by the Soviets that they assigned a full-time KGB agent to spy on him. Craven takes readers inside the highly secret DSSP and DSRV programmes, both of which offered crucial cover for sophisticated intelligence operations. He weaves a compelling tale of intrigue, both within the U.S. government and between the U.S. and Soviet navies providing an enthralling insider's account of how the submarine service kept the peace during the dangerous days of the Cold War.