for soldiers landing on the beaches. Strategic bombing, by contrast, was unlike anything the world has seen before or since. In 1940, the Germans attempted to force Britain to surrender through attacks on its airfields and factories, and then on its cities in The Blitz in what became the Battle of Britain, the first major battle whose outcome was determined primarily in the air. The campaigns conducted in Europe and Asia could involve thousands of aircraft dropping tens of thousands of tons of munitions over a single city. Military aviation in the post-war years was dominated by the needs of the Cold War. The postwar years saw a rapid conversion to jet power, which resulted in enormous increases in speeds and altitudes of aircraft. Until the advent of the intercontinental ballistic missile, major powers relied on high-altitude bombers to deliver their newly developed nuclear deterrent. Each country strove to develop the technology of bombers and the high-altitude fighters that could intercept them. The concept of air superiority began to play a heavy role in aircraft designs for both the United States and the Soviet Union. Post-World War II With the invention of nuclear weapons, the concept of full-scale war carries the prospect of global annihilation, and as such conflicts since WWII have been "low intensity" conflicts, typically in the form of proxy wars fought within local regional confines, using what are now referred to as "conventional weapons", typically combined with the use of asymmetric warfare tactics and applied use of intelligence. Nuclear warfare The use of nuclear weapons first came into being during the last months of WWII, with the dropping of atomic bombs on Hiroshima and Nagasaki. This was the only use of nuclear weapons in combat. For a decade after World War II, the United States and later the Soviet Union (and to a lesser extent the United Kingdom and France) developed and maintained a strategic force of bombers that would be able to attack any potential aggressor from bases inside their countries. Before the development of a capable strategic missile force in the Soviet Union, much of the war-fighting doctrine held by western nations revolved around the use of a large number of smaller nuclear weapons used in a tactical role. It is arguable if such use could be considered "limited" however, because it was believed that the US would use their own strategic weapons (mainly bombers