In July 1945, the decision was taken to end the war with Japan by using a new weapon, secretly worked on for years and with unprecedented destructive power. The US dropped the first atomic bomb, Little Boy, on Hiroshima on 6 August, followed three days later by Fat Man on Nagasaki (pictured here). The first, and to date only, use of nuclear weapons in war resulted in a death toll of roughly 200,000, with many more to follow due to radiation. Japan surrendered, but the impact of these weapons was felt around the world, sparking a nuclear arms race that would quickly evolve into the Cold War.