Almost since Truman drooped the bomb, historians have been claiming that he did so, not to end World War II but, instead, to fire the opening salvo in the Cold War. In other words, the post war academics claimed that Truman sacrificed hundreds of thousands of Japanese lives just to prove a point to Stalin.
For decades, the only writer to buck this trend was Paul Fussell in Thank God for the Atom Bomb, a book that I don’t believe ever got much traction. Fussell argued that Truman and his advisors, looking at the staggering US losses in Okinawa, and projecting ahead to a mainland invasion, predicted another 70,000 or more American dead, and 100,000 to 200,000 Japanese dead. Under these calculations, the bomb was a reasonable, even humane option.
It turns out Fussell was wrong. His numbers were too low. War historian Dennis Giangreco has examined many more documents that were released since Fussell’s book, and concluded that the best belief in 1945 was that a mainland assault would have been a bloodbath:
American planners for the invasion of Japan as far back as the summer of 1944 produced a worst-case scenario of “half a million American lives and many times that number wounded.” The Japanese Imperial Army’s increased efficiency at killing Americans, particularly on Okinawa, demonstrated to US Secretary of War Henry Stimson and many Pentagon planners that the worst case was a real possibility. This begged a question. The invasion of Japan was scheduled for fall 1945. If the situation on Okinawa — fully half a year before the invasion — was movng toward the original worse case scenario, was there an even worse case, unanticipated death toll? This notion alarmed Stimson. He ordered a multifaceted examination of the US Army’s manpower and training requirements. Shortly before the Potsdam Conference in July 1945, this resulted in an ominous warning: “We shall probably have to kill at least 5 to 10 million Japanese [and] this might cost us between 1.7 and 4 million casualties including 400,000 and 800,000 killed.”
You can read the rest of a fascinating and information interview with Mr. Giangreco here.