In the run-up to the planned invasion of Japan, physicist William Shockley was asked to prepare a casualty estimate for Secretary of War Henry Stimson. He calculated the twin invasions of the main Japanese islands, scheduled for the Fall of 1945 and the Spring of 1946, would result in as many as 1.7 million casualties, with 400-800,000 KIA—roughly the same number killed (on the low end) in all battles/all theaters up to that point. More conservative estimates from Admiral William Leahy put our expected combat deaths between 250-300,000. The number of Japanese dead would be in the millions.
Here’s another way of looking at the cost of invading Japan. Most of the Purple Hearts awarded to our dead and wounded in Afghanistan and Iraq came from stocks produced ahead of the planned amphibious landings in Japan. As of 2010, there were still more than 100,000 of those WWII medal kits still in defense supply warehouses.
A lot of us wouldn’t be here today if the U.S. hadn’t dropped the bombs on Hiroshima and Nagasaki. My father was part of the 1st Army that fought its way across Europe after D-Day. Plans called for the 1st to lead the invasion of Honshu in the spring of 1946, with the objective of taking Tokyo. It would have been a bloody, protracted campaign, and a lot of ETO vets did not expect to make it through a second campaign against Japan.
Same here. My Dad's division was part of the 3rd and later the 7th armies, making the long slog across Europe from D-Day to the Ruhr Valley. He never talked much about his experiences, but did say the second-happiest day of his life was hearing the news that the bombs had fallen and the war was likely over, which would spare him and his friends another amphibious assault on enemy-held ground. So he was able to come home and marry the girl he left behind, which was the happiest day of his life.