Towards the end of WWII the allies had a plan for the invasion of the Niphon home islands. But with the Soviet Union declaring war on the land of the rising sun, and the Americans dropping two nukes on them the Nipponese surrendered before the operation had to be implemented.
But I was thinking of what if Truman didn't drop the bombs, or the US didn't have them in time. Due to Niphons terrian the Nipponese military knew where the allies would attack and planned accordingly. Though I have now doubt that the Allies and soviets would have won the fight, with casualties possibly in the millions for all sides, tens of millions for the Nipponese, in an invasion that could have took up to five years.
I'm more interested in the Post war effects for Niphon. Would it be stuck in the same situation that post war Germany was in, and be wouldn't reunited tell the fall of the Soviets some forty years later. Or is there other possibilities that I'm not seeing.
Or also on the flip side had the Americans had the nukes, but the Soviets picked not to go to war with Niphon. Would they have still surrendered, or would they have felt that they could hold off the onslaught of the Allies and their nukes, I think not.
EDIT: I just realized this is in the wrong area, sorry