In August 1945 atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki, hastening the end of the Second World War and heralding the birth of the atomic age.
International attempts to control the development of nuclear technology quickly stalled, leading to a race between the United States, the Soviet Union, Britain and France to develop their own nuclear weapons. These countries adopted a policy of nuclear deterrence, using the threat of massive retaliation to prevent a nuclear attack by an enemy.
The McMahon Act of 1946 prevented Britain from co-operating with the United States on nuclear research and development, yet Britain has been a major player in the atomic age, conducting its own atomic weapons testing programme and opening the world's first commercial nuclear power station at Calder Hall in Cumbria in 1956.
Although many view the atomic age positively, others such as the Campaign for Nuclear Disarmament view atomic technology as a threat to the world's future and have been protesting against its development and use since the late 1950s.