This is the fourth part of our series on the atomic bomb.
IV. Military Situation, July 31, 1945
Thirteen American divisions were scheduled to land on the island of Kyushu in November 1945, an operation twice as large as D-Day. Sixteen American divisions would invade Honshu in March 1946. One million American casualties were expected. The Japanese were prepared to resist to the last woman and child, planning for civilians to attack the Americans with sharpened bamboo sticks in suicidal human wave attacks. There are no estimates for the number of Japanese who would have died in an invasion, but they would have been at least several million, since the American planners believed that it would take until November 1946 to mop up the last Japanese resistance. (They were basing their projections on what they'd learned at Okinawa and Iwo Jima and Saipan and Guadalcanal and Manila and Tarawa and Tinian.) Meanwhile, the British were going to invade the Malay Peninsula with six divisions, 200,000 men, an operation as large as D-Day, and retake Singapore, on September 9, 1945. They expected fighting to last until March 1946. That fighting alone would have cost 50,000 British soldiers' and perhaps five times as many Japanese lives.
Said former U.S. Army Captain Harry Truman, who had commanded an artillery battery on the Western Front in 1918 and who had actually been in a war, on the front lines, and seen hundreds or thousands of people die, "Having found the bomb, we have used it. We have used it to shorten the agony of young Americans."
(Source: Thank God for the Atom Bomb, Paul Fussell)