The years 1945-61 saw the greatest transformation in weaponry that has ever taken place, as atomic and thermonuclear bombs, intercontinental ballistic missiles and chemical and biological weapons were developed by the superpowers. It was also a distinct era in Western intelligence collection. These were the years of the Germans. Mass interrogation in West Germany and spying in East Germany represented the most important source of intelligence on Soviet war-related science, weapons development and military capability until 1956 and a key one until 1961. This intelligence fuelled the arms race and influenced Western scientific research, weapons development, and intelligence collection. Using intelligence and policy documents held in British and US archives and records of the Ministry of State Security (MfS) of the former German Democratic Republic (GDR), this book is the most penetrating study of the scientific intelligence-gathering and subversive operations of the British, US, and West German intelligence services in the period to date.East Germany's scientific potential was contained by inducing leading scientists and engineers to defect to the West, and Paul Maddrell shows that the US Government's policy of 'containment' was more aggressive than has hitherto been accepted. He also demonstrates that the Western secret services' espionage in the GDR was very successful, even though the MfS and KGB achieved triumphs against them. George Blake twice did appalling damage the MI6's spy networks. The book reveals the identity of the most distinguished scientist to spy for the CIA as yet uncovered.