Debate over the bomb started early after the War was won and the American troops who would quite likely have died in an invasion of the Home Islands safely demobilized and back home in the states. I have recently come across a fascinating article which appeared in The Atlantic in 1946 defending the use of the atomic bomb. The article was written by Karl T. Compton. A prominent physicist and President of MIT, he had served on the committee that recommended use of the bomb. He sums up the case in favor of the bomb as follows:
The evidence points to a combination of factors. (1) Some of the more informed and intelligent elements in Japanese official circles realized that they were fighting a losing battle and that complete destruction lay ahead if the war continued. These elements, however, were not powerful enough to sway the situation against the dominating Army organization, backed by the profiteering industrialists, the peasants, and the ignorant masses. (2) The atomic bomb introduced a dramatic new element into the situation, which strengthened the hands of those who sought peace and provided a face-saving argument for those who had hitherto advocated continued war. (3) When the second atomic bomb was dropped, it became clear that this was not an isolated weapon, but that there were others to follow. With dread prospect of a deluge of these terrible bombs and no possibility of preventing them, the argument for surrender was made convincing. This I believe to be the true picture of the effect of the atomic bomb in bringing the war to a sudden end, with Japan’s unconditional surrender.
If the atomic bomb had not been used, evidence like that I have cited points to the practical certainty that there would have been many more months of death and destruction on an enormous scale. Also the early timing of its use was fortunate for a reason which could not have been anticipated. If the invasion plans had proceeded as scheduled, October, 1945, would have seen Okinawa covered with airplanes and its harbors crowded with landing craft poised for the attack. The typhoon which struck Okinawa in that month would have wrecked the invasion plans with a military disaster comparable to Pearl Harbor.
These are some of the facts which lead those who know them, and especially those who had to base decisions on them, to feel that there is much delusion and wishful thinking among those after-the-event strategists who now deplore the use of the atomic bomb on the ground that its use was inhuman or that it was unnecessary because Japan was already beaten. And it was not one atomic bomb, or two, which brought surrender; it was the experience of what an atomic bomb will actually do to a community, plus the dread of many more, that was effective.