US Government Photo Harold Agnew carrying the plutonium core of the Nagasaki Fat Man bomb in 1945.
Nicknamed after Winston Churchill, "Fat Man" was the second nuclear weapon to be deployed in combat after the US dropped a 5-ton atomic bomb on the Japanese city of Hiroshima.
Agnew, who became the third director of the Los Alamos Laboratory, flew in a plane along slide Enola Gay and took the only footage of the attack from a bird's eye view.
Here is a clip of the film he captured:
YouTube/Amanda Macias/Business Insider
Of the 10,800 pound "Fat Man" bomb, approximately two pounds underwent a fission reaction and a gram of that yielded an explosion equivalent to 21,000 tons of TNT, according to the Atomic Heritage Foundation.