During the summer of ’45 – the first nuclear bomb exploded over New Mexico, exceeding everyone’s wildest expectations.
0.016 seconds after detonation. 600 feet wide. The light visible 180 miles away.
Truman never hesitated for a second about using the bomb to force Japan to surrender. Many issues and lots of politics went into this decision. First, an estimated 250.000 US troops would be killed on the shores of Japan in the case of an invasion, which was the alternative. Better then to wipe out one or two japanese cities, with casualties estimated to 20-30.000 each. Routinely bombing raids with hundreds of B-29s already killed 100.000 – 200.000 a day towards the end of the war.
Second, FDR had alreadyspent $2 billion on the Manhattan Project. Not using the weapon was thus considered illogical.
Furthermore, the “allied” status of Russia was extremely problematic, and another war could easily break out over the satellite states of Eastern Europe. The soviets would have the bomb in a few years time, or so went the reasoning.
The deterrent effect of power. Everyone wanted an immediate end to the war after six years and sixty million killed. The shock of a new weapon – wiping out a city – would stop everything.
Establishing US supremacy. Even if the russians would get the bomb later, the politics of being first must have been irresistable – considering the other arguments of reducing casualities and suffering in the bigger picture.
Truman was also a veteran from WWI, leading an artillery battery, experiencing the amoral decisions of war on the ground. Killing to prevent more killing. Even as a later small county judge he was exposed to decisions of permitting small crimes to prevent bigger crimes. He struggled with these dilemmas for a while, but found peace with accepting the concept of choosing the lesser evil.
All in all – people were weary – and wanted to go home. To save lives, prevent more killing and secure long-term peace – there was really no hesitation regarding the decision. According to Truman, he made up his mind and went to bed, sleeping well.
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