An estimated 220,000 died from the bombs at Hiroshima & Nagasaki....that amount would’ve be 10x had the US & allies been forced to attack the Jap mainland, which would’ve been the only way to end the war and get the Japs to surrender...
In the lead up to the planned land invasion of Japan, the War Department placed an order for 500,000 Purple Hearts. We continue to draw from that requisition today.
I'm not a big fan of estimates on the atom bomb deaths. The 1946 estimates by the Manhattan Project were 78K Hiroshima and 35K Nagasaki. Perhaps underplayed so that the U.S. doesn't look evil. Estimates since the 1970s (after it became fashionable to say the U.S. is all things evil) are 140K Hiroshima and 70K Nagasaki.
I don't like either estimates because I don't like people playing with numbers to send a message, in either direction.
This I know for sure from poxy measurements:
1) Total Japanese deaths from the island hopping: not enough for Japan to surrender.
2) Total deaths from firebombing mainland Japan (plus prior deaths): not enough for Japan to surrender.
3) Total deaths from 1st atom bomb (plus prior deaths): not enough for Japan to surrender.
4) Total deaths from 2nd atom bomb: enough for Japan to surrender, and that's what mattered most.
VDH has an excellent YouTube layout of the choices facing the Allies...