For righteous in my mentions re the Atomic Bomb: here is the Op Downfall planning map .... MacArthur's casualty numbers were by mid-1945 still low - but his future casualty estimates had been reliably accurate thru WW2 & his estimated KIA/WIA for invading Japan were astronomical.

When you look at this map, you will note, for the initial assault, all the units were American. The Australians, British, Canadians etal would support the invasion but were by mid-1945 thoroughly committed in Europe & the Middle East. Allied manpower was almost exhausted.

The only alternative source of manpower for invading Japan would likely have been a northern Soviet pincer, which to avoid a massive casualty bill, would have risked a Japan part occupied by the Soviets. Imagine a divided Japan like a divided Germany? Exaggerated meme? Perhaps?

The Atomic Bomb(s) allowed the Allies (under MacArthur) to rapidly occupy Japan *without* the Soviets in the 4 home islands. As a result, MacArthur could rule as a Shogun - and feed & rebuild Japan - without any Soviet zone (the Sakhalins notwithstanding).

I call this our "annual flogging of dead horses (atomic bomb edition)" because people in 2020 have no idea just how exhausted all the Allies were in Aug 1945 & how simply out of manpower the non-US Allies were when examining the prospect of invading Japan (while occupying Europe)

This is simply not true - even when the Emperor was trying to address the Japanese people, his high command was trying to stop it. And no one at the time with access to Ultra, Magic, JN25 & after, believed the Japanese would surrender. https://twitter.com/latimes/status/1291376233230598148

Always recall, when someone says, "well, the Japanese might have surrendered", that the US, for example, is, even now, still drawing down the massive Purple Heart stockpile it minted for the enormous casualty toll expected from an Op Downfall/Japan invasion in 1945-1946 ....

I am not a reflexive critic of Obama's but what is this??? "The memory of August 6, 1945" for many Allied troops & their families was, likely, "We may just be spared being killed / wounded invading Japan". https://twitter.com/BarackObama/status/1291440263404167177

The "American Caesar" series on MacArthur is excellent but here the simple explanation by William Manchester of how MacArthur's (historically accurate) casualty estimates for invading Japan persuaded Truman to drop the atomic bomb

The initial plan for invading Japan in late 1945 assumed a heavily-opposed lodgement by 4 separate Allied Armies, which would be reinforced in Jun 1946 by 4 Divisions per month. The official US Army history below & note MacArthur's intelligence estimate:

https://history.army.mil/books/wwii/MacArthur%20Reports/MacArthur%20V1/ch13.htm