Operation Downfall called for SIXTEEN atomic bombs. Basically nuke it, march through the fallout, nuke it, march through the fallout, nuke it, march through the fallout, up to Tokyo. And if they had to keep going after that well, the US will have had time to make more bombs.

People forget that the B-29 was more expensive and more of a strategic priority than the Manhattan Project. People also forget that Germany spent more on the V-2 than the US spent on the Atomic Bomb. "Big boom" is the horror weapon we all freak out about now but the WWII mentality was "the way we win this is by indiscriminate unguided bombing at scale from an extreme distance."

We've created this false narrative around "should the US have used a horrific weapon like the atomic bomb" when the real dilemma, acknowledged by both the United States and Japan, was "will the Japanese be made extinct as an ethnicity before hostilities are over." The truth of the situation is the Emperor of Japan saw Hiroshima, went "stop this madness", was nearly murdered by a military junta, and enough loyalists regained control for the Emperor to declare unconditional surrender after Nagasaki. Anyone who wants to waffle around the absolute and total genocide anticipated by both sides of the conflict is a simp. We were gonna turn Japan into Carthage and the Japanese were all in on it.