The first nuclear weapon used in war was a gun-type uranium-235 device dropped on Hiroshima by the B-29 Enola Gay on 6 August 1945, killing an estimated 70,000 people instantly. It was never tested before use because its simple gun-barrel design was considered certain to work, unlike the implosion design tested at Trinity. Less than a kilogram of its 64 kilograms of uranium actually underwent fission.
Photograph of a Little Boy nuclear bomb, the same type of weapon dropped on Hiroshima, Japan, in August 1945. This was the first photograph of a Little Boy bomb casing to ever be released by the U.S. government (it was dUS Atomic Energy Commission (now US Department of Energy) · Public domain · source · Public domain · sourceA-Bomb. LB (Little Boy) unit on trailer cradle in pit on Tinian island, before being loaded into Enola Gay's bomb bay. [Note bomb bay door in upper right-hand corner.] , 08/1945. ARC Identifier: 519394.Unknown authorUnknown author · Public domain · source
![A-Bomb. LB (Little Boy) unit on trailer cradle in pit on Tinian island, before being loaded into Enola Gay's bomb bay. [Note bomb bay door in upper right-hand corner.] , 08/1945. ARC Identifier: 519394.](/photos/little-boy-3.jpg)
