Remember, it took two atomic bombs to force a Japanese surrender and that decision came directly from the emperor. A military coup overthrowing the emperor was almost successful. Dropping those two bombs saved countless civilian lives in Japan.
http://en.wikipedia.org/wiki/Operation_Downfall
"In addition, the Japanese had organized the Patriotic Citizens Fighting Corps — which included all healthy men aged 15–60 and women 17–40 — to perform combat support, and ultimately combat jobs. Weapons, training, and uniforms were generally lacking: some men were armed with nothing better than muzzle-loading muskets, longbows, or bamboo spears; nevertheless, they were expected to make do with what they had.[19]"
"One mobilized high school girl, Yukiko Kasai, found herself issued an awl and told, 'Even killing one American soldier will do. … You must aim for the abdomen.'[20]
"Casualty estimates were based on the experience of the preceding campaigns, drawing different lessons:
In a study done by the Joint Chiefs of Staff in April, the figures of 7.45 casualties/1,000 man-days and 1.78 fatalities/1,000 man-days were developed. This implied that a 90-day Olympic campaign would cost 456,000 casualties, including 109,000 dead or missing. If Coronet took another 90 days, the combined cost would be 1,200,000 casualties, with 267,000 fatalities.[33]
A study done by Adm. Nimitz's staff in May estimated 49,000 casualties in the first 30 days, including 5,000 at sea.[34] A study done by General MacArthur's staff in June estimated 23,000 in the first 30 days and 125,000 after 120 days.[35] When these figures were questioned by General Marshall, MacArthur submitted a revised estimate of 105,000, in part by deducting wounded men able to return to duty.[36]
In a conference with President Truman on June 18, Marshall, taking the Battle of Luzon as the best model for Olympic, thought the Americans would suffer 31,000 casualties in the first 30 days (and ultimately 20% of Japanese casualties, which implied a total of 70,000 casualties).[37] Adm. Leahy, more impressed by the Battle of Okinawa, thought the American forces would suffer a 35% casualty rate (implying an ultimate toll of 268,000).[38] Admiral King thought that casualties in the first 30 days would fall between Luzon and Okinawa, i.e., between 31,000 and 41,000.[39]
Of these estimates, only Nimitz's included losses of the forces at sea, though kamikazes had inflicted 1.78 fatalities per kamikaze pilot in the Battle of Okinawa,[40] and troop transports off Kyūshū would have been much more exposed.
A study done for Secretary of War Henry Stimson's staff by William Shockley estimated that conquering Japan would cost 1.7 to 4 million American casualties, including 400,000 to 800,000 fatalities, and five to ten million Japanese fatalities. The key assumption was large-scale participation by civilians in the defense of Japan.[1]
Outside the government, well-informed civilians were also making guesses. Kyle Palmer, war correspondent for the Los Angeles Times, said half a million to a million Americans would die by the end of the war. Herbert Hoover, in memorandums submitted to Truman and Stimson, also estimated 500,000 to 1,000,000 fatalities, and were believed to be conservative estimates; but it is not known if Hoover discussed these specific figures in his meetings with Truman. The chief of the Army Operations division thought them "entirely too high" under "our present plan of campaign."[41]
For context, the Battle of Normandy had cost 63,000 casualties in the first 48 days; and the Battle of Okinawa ran up 72,000 casualties over about 82 days, of whom 18,900 were killed or missing. Several thousand soldiers who died indirectly whether from wounds or other causes at a later date are not included. The entire war cost the United States a total of just over a million casualties, with 400,000 fatalities.
Nearly 500,000 Purple Heart medals were manufactured in anticipation of the casualties resulting from the invasion of Japan. To the present date, all the American military casualties of the sixty years following the end of World War II — including the Korean and Vietnam Wars — have not exceeded that number. In 2003, there were still 120,000 of these Purple Heart medals in stock.[42] There are so many in surplus that combat units in Iraq and Afghanistan are able to keep Purple Hearts on-hand for immediate award to wounded soldiers on the field.[42]"