Thanks Northern Yankee. Had the Bomb not made it in time, or just remained unused, the land invasion would have been hideously costly — but of course would have been preceded by conventional firebombing, which had nearly leveled almost four dozen Japanese cities and killed tens or hundreds of thousands. The island would have been cut off from needed supplies, starved out, deurbanized, disarmed (the hard way), and, okay, so now I’m starting to get the blue light going, I’d better stop... ;’)Not only that, but most likely the Soviets would have gotten involved, and then you would have probably had a Japanese Civil War afterwards, ala Korea.
No doubt, although (due to lack of amphibious capability) they’d have likely just occupied, say, Korea, after pushing the Japanese down the peninsula. Then, maybe no Korean War...