On 16 July 1945, the first atomic bomb tests were held in top secrecy in the New Mexico desert.

The team of allied scientists working on the bomb were present for the explosion, but none was prepared for the full extent of the devastation.

Justifying themselves with the argument that the 'enemy might get there first', the allies ploughed on, developing another more devastating weapon: the hydrogen bomb.

Watch original footage from the tests, and hear Oppenheimer's reminiscences, in this British Pathé video, above.