They also saved many Japanese lives, including civilians. The land of the kamikaze pilots was not going to go down easily.
My uncle was on an LST bound for Japan when Hiroshima happened. He had just finished going from landing to complettion on Okinawa, a campaign that cost his unit over 100% casualties, "red boot" replacements from Hawaii arriving all the time. They were called red boot because the red volcanic dirt of Hawaii they had been training in stood out from Okinawan soil.
There were virtually no POWs taken in Okinawa. End of campaign, hundreds, possibly thousands of Japanese troops leapt off the ocean cliffs rather than surrender, and I know of no American POWs retieved. Every man out of Okinawa knew what to expect as a level of resistance in a homeland invasion. Hiroshima and Nagasaki saved more Japanese lives than American. Men, women and children from 8 to 80 literally were supplied with sticks, bricks and pitchforks with which to defend the Emporer.
As an aside, uncle has tried for some years to contact anyone caught in the storm his vessel survived. Anyone with personal knowledge, please reply. Uncle is 79 and his mates are dwindling all the time.
SSQ's Daddy always said that he was alive only because of the bombs. He was slated to be in the invasion force in the Fall of 1945.