Portent

The Fat Man fission bomb was the second and last atomic weapon to be used in war.  The original Fat Man was deployed over Nagasaki, Japan in August of 1945 by Bockscar, the B-29 pictured behind the bomb.  It detonated with a yield of 21 kilotons at an altitude of 1,800' when high explosives compressed the plutonium core to supercritical density.