The Manhattan Pacifists
Ironically, the two scientists most responsible for creating the atomic bomb were both pacifists. Leo Szilard, the first scientist to seriously examine the science behind the creation of nuclear weapons was instrumental in the development of the Manhattan Project. Before World War II, "Szilard had considered the U.S. the one truly humane government in the world; that is why he chose to assist them, over everyone else, with the atomic bomb. He resigned from this view after the U.S. used the weapons at the conclusion of the war." He also argued that "if the Germans had dropped atomic bombs on cities instead of us, we would have defined the dropping of atomic bombs on cities as a war crime, and we would have sentenced the Germans who were guilty of this crime to death at Nuremberg and hanged them." Albert Einstein considered himself a pacifist. He once said, "I believe Gandhi's views were the most enlightened of all the political men of our time. We should strive to do things in his spirit: not to use violence for fighting for our cause, but by non-participation of anything you believe is evil."
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By the time the first atomic bomb was completed, Germany had already surrendered. At that time, the Japanese war effort was reduced to suicide missions by young, inexperienced pilots pressed into service by a fanantical group of militarists who were absolutely opposed to the idea of surrender. The Allied supreme command took the view that a full-scale invasion of the island nation would take several months and result in an inordinate amount of casualties, both civilian (read: innoncent Japanese citizens) and military.
Sadly, the two bombs were justified as a compromise between what was viewed as the lesser of two evils.
I am not well-versed in WW2 history. A question in my mind is, since the scientists had informed the military of the atomic bomb's destructive potential, did the supreme command debate its deployment in a part of the island that was relatively isolated? In their minds, would that have been enough to convince the fanatical militarists that further resistance was futile?
In the aftermath, the pilots and crew chosen for the two missions have always maintained personal views of the rightness of their actions.
The Nuremburg trial, however, was monumental, due to its unique, at the time, view of crimes against humanity. The tribunal took the view that soldiers couldn't use the excuse of following orders in circumstances outside of traditional combat. The tribunal held the view that soldiers had a moral imperative to disobey in circustances involving the killing of innocent civilians. The tribunal made an exception concerning matters in which soldiers themselves risked being executed if they disobeyed, for example, an order to kill Jewish prisoners in concentration camps.
At some basic level, war makes monsters of us all. Of course, we have witnessed through the ages how monsters can return to being men.
And we have also witnessed how some monsters are apparently incapable of returning to what would be considered a humane state of consciousness.
Our choices define us.

Scientists are the most gullible people in the world, followed by politicians and philosophers. And investors.