This dissertation is a historical study of one of the most important American figures of the Cold War, General Curtis Emerson LeMay, and his role in shaping the actual nuclear policy of the United States during the first decade of the Cold War, 1945 to 1957. LeMay was the second and most influential commander of the U.S. Air Force’s Strategic Air Command (SAC), America’s nuclear bomber force. This dissertation argues that, LeMay, in his position as the military commander of SAC, advocated for the consideration of preemptive nuclear strikes against the Soviet Union-had it become clear that the Soviets were preparing to attack the United States. LeMay built and oriented SAC for just such a purpose. This was achieved through SAC’s receipt of nuclear weapons custody and development of the “alert force,” bombers armed with nuclear weapons and their crews trained and ready for immediate departure to attack the Soviet nuclear force. LeMay’s efforts and statements marked a departure from the declared American policy of containment through nuclear deterrence, demonstrating that the policy publicly proclaimed by American officials differed from the policy SAC was prepared to execute.