On 11 June, a group of B-29s began to arrive at Tinian's North Field, and parked its aircraft in a guarded and sequestered section of that sprawling complex. Combat flight training started for the 509th Composite Group on 30 June. On 20 July, the group began a string of a dozen strikes against carefully chosen Japanese cities, flying the missions with two to six planes and dropping single bulbous bombs.

General Spaatz, commanding the US Strategic Air Forces, received a secret order on 24 July. It informed him that the 509th CG would drop its first special bomb on any one of four cities: Hiroshima, Kokura, Niigata or Nagasaki. The attack would be made as soon as weather permitted visual bombing but not before 3 August.

The special bomb was, of course, the first atomic weapon, 'Little Boy', ready since 31 July. The weather had been bad for a spell, but it looked good for August and LeMay issued the orders for Special Bombing Mission 13. Hiroshima's urban industrial area was the primary target; secondary was Kokura and its arsenal; tertiary was the urban area of Nagasaki. Mission details were very specific: bomb altitude was to be between 28,000 and 30,000 ft (8,550 and 9,150 m); speed, 200 mph (320 km/h); both pilot and bombardier had to see and agree on the target; bombing had to be by visual means.

The rest of the story has been told time and again in many contexts. There is one important point: Hiroshima was blown out of existence on 6 August 1945.