FM (Fat Man) unit being placed on trailer cradle in front of Assembly Building #2, August 1945

Fat Man, was used at Nagasaki, Japan at 11:02 09 August 1945. It had the equivalent destructive force of 21,000 tons of TNT and exploded at 1650 feet / 503 meters altitude

Photo: War Department
Office of the Chief of Engineers
Manhattan Engineer District
National Archives and Records Administration
College Park, Maryland