"Little Boy" detonated 1,870 feet above ground 43 seconds after it was released from the Enola Gay. The explosion equaled about 13,000-15,000 tons of TNT. The distinctive T-shaped Aioi Bridge was ground zero.

Never in the history of warfare had any weapon caused such massive destruction. Thousands of people died. Many were vaporized. Some sustained strange burn patterns from heat waves on their clothes. Others developed a new illness: radiation sickness. Hiroshima was demolished and its people devastated.

By the time Enola Gay had returned to Tinian Island, "psychological warfare" leaflets were ready to be dropped on other Japanese cities. Urging the people to evacuate their homes, the Americans warned:

Before we use this bomb again and again to destroy every resource of the military by which they are prolonging this useless war, petition the Emperor now to end the war.

America had one more bomb that was ready for delivery. Three days later it was assembled and loaded onto Bockscar, another B-29. This time the target was Nagasaki (because the primary target, Kokura, was obscured by smoke and haze).