User blog comment:NovaSims/What WW2 have been like if Hitler adnt attacked Russia and Japan hadnt attacked America?/@comment-4621372-20120909190549/@comment-9906822-20120909214103

The atomic bombings directly killed 150,000 to 246,000 people. Even if we were able to determine exactly how many people succumbed to radiation poisoning in the years following, that number would once again pale in comparison to the military and civilian casualties resulting from an invasion of the Home Islands. This, because you only listed the initial casualties that would come from landing and securing the beachheads. Don't forget that once the first month has passed and the Allies have broken out, the task of securing every staunchly defended inch of the country still awaits.

Like Nazi Germany in her last days, Japanese soldier and civilian alike will be roused by the military government to stand and fight to the death against the "foreign devils", engaging in guerilla warfare and suicide attacks (a la Kamikaze, Banzai charges, et cetera). And once that monstrous task has been completed, the Americans will have no choice but to dispose of Hirohito, the God Emperor, which will ensure that the country will remain in upheaval and the Allies will have to occupy the country much more actively than they did in OTL.

Quoting the Wikipedia article: ''A study done for Secretary of War Henry Stimson's staff by William Shockley estimated that conquering Japan would cost 1.7-4 million American casualties, including 400,000–800,000 fatalities, and five to ten million Japanese fatalities. The key assumption was large-scale participation by civilians in the defense of Japan.''

And that's just the military conquest. Add to that the casualties grossed from the no doubt violent occupation and the social trauma caused by the murder and rape of Japanese women and children at the hands of the occupation force and realize that the bombings were a quicker and more "humane" way to break the Japanese fighting spirit.