On August 6, 1945, the US dropped atomic bombs on the Japanese city of Hiroshima, following up three days later with another bomb on Nagasaki.
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.
Soldiers check the casings on the 'Fat Man' atomic bomb. Multiple test bombs were created on Tinian Island. All were roughly identical to an operational bomb, even though they lacked the necessary equipment to detonate.
On the left, geophysicist and Manhattan Project participant Francis Birch marks the bomb unit that would become 'Little Boy,' while Norman Ramsey, who would later win the Nobel Prize in physics, looks on.
A technician applies sealant and putty to the crevices of 'Fat Man,' a final preparation to make sure the environment inside the bomb would be stable enough to create a full impact once it detonated.
At the airfield, 'Fat Man' is lined up over a pit specifically constructed for it, from which it is then loaded into the plane that eventually dropped it over Nagasaki.
Both pits for 'Little Boy' and 'Fat Man,' each roughly 8 feet by 12 feet, still exist today on the island and now serve as a memorial of sorts.
Workers check 'Little Boy' one last time, keeping the tarp on for security reasons, following a lowering procedure similar to the one done for 'Fat Man' three days later.
Once 'Little Boy' is ready, the Enola Gay, a Boeing B-29 Superfortress bomber, is reversed and positioned over the trench.
Using the hydraulic lift, 'Little Boy' is carefully raised and loaded into the belly of the Enola Gay.
NOW WATCH: Briefing videos
Business Insider Emails & Alerts
Site highlights each day to your inbox.