It's been sitting on my shelf for years, but I finally read Gar Alperovitz's The Decision to Use the Atomic Bomb. I'm regret letting it wait so long, since the book is as close to a definitive word on the subject as we're likely to see unless important new evidence emerges.
Alperovitz produces the documentary evidence to prove that Truman and other US leaders knew that Japan was on the verge of collapse, that the Japanese' worst nightmare was about to come true (Russia was entering the war against them), and that the Japanese were looking for a way to surrender. American military leaders fully believed that Japan had little chance of holding out until an invasion began (still seven months away), let alone resisting long after. Despite this conviction, they used atomic bombs to destroy not one, but two cities, deliberately targeting civilian populations rather than military installations. This much is really not arguable.
They believed that Japanese leaders needed a major shock to convince them to quit, but had expected all along that the Russian attack would do the trick. But here was the dilemma: the Russians could hasten the end of the war, but they also strengthen their position in Asia after the war. Soviet-American rivalry was already in motion. Alperovitz believes that the bombings were meant to make sure the Japanese surrendered ASAP - not just before the Americans had to invade, but before the Russians could have much to do with it. Also, a truly horrific display was expected to impress Stalin tremendously, perhaps making him a little more tractable later on.
Alperovitz believes the last factor - scaring the Russians - was a huge factor, because it's otherwise hard to explain why the Americans deliberately made it harder for the Japanese to surrender earlier. While Japan would have liked to hold onto any part of their mainland conquests, if possible, they were ready to give up all but one thing - they would not let the Americans depose Hirohito, especially when they could see what was about to happen to defeated German leaders at Nuremberg. All of the well-known talk of Japanese fighting to the last man was predicated on this belief that they would be fighting to protect their emperor. On the other hand, the one authority who could compel Japanese soldiers to lay down arms was, of course, the emperor.
Thus, it seems perverse that the Potsdam Declaration demanded "unconditional surrender" with no guarantee for the emperor. Nor was it an oversight: the language of such a guarantee was removed from the final draft of the Declaration. The Japanese asked for clarifications, but didn't receive any and didn't believe they could consider surrender under those circumstances. Eventually, of course, the emperor was retained, he did order his people to surrender, and they did. Considering that Hirohito had already initiated peace feelers through the USSR (before the Russians declared war themselves), and that the Americans knew all about it, Alperovitz provocatively suggests that the decision to use the bombs might have actually prolonged the war by a few weeks.
After the bombings, in response to a fairly small number of critical voices, Alperovitz argues that a myth of military necessity was consciously constructed to protect the American reputation (sound familiar? retain the moral high ground by controlling the story, not by restraining your actions). The famous figure of 1,000,000 lives saved by the bombings come from these actions - there is no documentary support for such an analysis anywhere and actual contemporary documents argue explicitly against the likelihood of so many casualties. Several of the top brass were quite straightforward (although not especially loud) in stating that the bombs made little or no contribution to the end of the war. But after Secretary of War Henry Stimson was convinced to put his name to a 1947 article inHarper's arguing otherwise, then the matter was settled for most Americans. Alperovitz devotes almost half of his 800-page book to this Myth-making effort.
As a PS, finishing the book provoked me to watch "Tora! Tora! Tora!" again last night and it's still an excellent work. A joint US-Japanese effort that doesn't seem to grind many axes, it rises above some rather pedestrian acting and tells an extremely compelling story. All without a dramatic musical score, too.