National Archives
The bombs, known as "Little Boy" and "Fat Man," were loaded onto bombers at the North Field airbase on Tinian Island in the Northern Mariana Islands, which are south of Japan.
Until recently, few photographs of the run up to the attacks were available.
But declassified pictures shed light on the preparations for the bombings - the first and only wartime nuclear bombings in history.
While seemingly mundane, these photos show us what it was like to prepare for one of the most important moments in modern history.
First seen on AlternativeWars.com. An earlier version of this post was composed by Christian Storm.