The notion that the alternative to the bombings was an invasion is an utterly pernicious falsehood. It is a matter of record that Japan had offered to surrender prior to the bombings, conditional only upon retaining the emperor. Those terms were subsequently accepted, after the bombings. The "peace" faction's strategy was to accept the surrender before conducting the bombings.

There is a 1950s fictional film by Akira Kurosawa called "I Live in Fear" which tells the story of a man driven mad by fear of radiation from a nuclear war. For better or worse it is easy to forget now what a catastrophic thing the introduction of the bomb was for everyone.

What if 4 or 5 years after the war it turns out that the president had a wonder weapon that could have ended the war in a week and saved 1/2 a million GI's - it would have been the end for the democratic party when that came out.