Eatherly was the pilot of Straight Flush, one of seven B-29s of the 393d Bomb Squadron of the 509th Composite Group that took part in the Hiroshima mission, which was the culmination of ten months of training during World War II.

[citation needed] After reporting the weather was good over the target, Eatherly turned Straight Flush for home, and was over 300 miles (480 km) from ground zero when the bomb exploded.

The plot was uncovered, and Eatherly was arrested and prosecuted, serving time in jail for this offense.Eatherly claimed to have become horrified by his participation in the Hiroshima bombing, and hopeless at the possibility of repenting for or earning forgiveness for willfully extinguishing so many lives and causing so much pain.

At one point "he set out to try to discredit the popular myth of the war hero [by] committing petty crimes from which he derived no benefit: he was tried for various forgeries and forged a check for a small amount and contributed the money to a fund for the children of Hiroshima.

[citation needed] It was in this hospital that he began to correspond with Günther Anders, a German philosopher and pacifist, who became his friend in a battle to promote the abolition of nuclear weapons.

Eatherly wrote: Whilst in no sense, I hope, either a religious or a political fanatic, I have for some time felt convinced that the crisis in which we are all involved is one calling for a thorough re-examination of our whole scheme of values and of loyalties.

On the contrary I believe that we are rapidly approaching a situation in which we shall be compelled to re-examine our willingness to surrender responsibility for our thoughts and actions to some social institution such as the political party, trade union, church or State.