The Japanese were ready to surrender three months before being atom bombed, and Truman knew it. Nevertheless, the bombs were dropped. From John V. Denson at mises.org:
Every year during the first two weeks of August the mass news media and many politicians at the national level trot out the “patriotic” political myth that the dropping of the two atomic bombs on Japan in August of 1945 caused them to surrender, and thereby saved the lives of anywhere from five hundred thousand to 1 million American soldiers, who did not have to invade the islands. Opinion polls over the last fifty years show that American citizens overwhelmingly (between 80 and 90 percent) believe this false history which, of course, makes them feel better about killing hundreds of thousands of Japanese civilians (mostly women and children) and saving American lives to accomplish the ending of the war.
The best book, in my opinion, to explode this myth is The Decision to Use the Bomb by Gar Alperovitz, because it not only explains the real reasons the bombs were dropped, but also gives a detailed history of how and why the myth was created that this slaughter of innocent civilians was justified, and therefore morally acceptable. The essential problem starts with President Franklin Roosevelt’s policy of unconditional surrender, which was reluctantly adopted by Churchill and Stalin, and which President Truman decided to adopt when he succeeded Roosevelt in April of 1945. Hanson Baldwin was the principal writer for the New York Times who covered World War II and he wrote an important book immediately after the war entitled Great Mistakes of the War. Baldwin concludes that the unconditional surrender policy
was perhaps the biggest political mistake of the war….Unconditional surrender was an open invitation to unconditional resistance; it discouraged opposition to Hitler, probably lengthened the war, cost us lives, and helped to lead to the present aborted peace.
The stark fact is that the Japanese leaders, both military and civilian, including the emperor, were willing to surrender in May of 1945 if the emperor could remain in place and not be subjected to a war crimes trial after the war. This fact became known to President Truman as early as May of 1945. The Japanese monarchy was one of the oldest in all of history, dating back to 660 BC. The Japanese religion added the belief that all the emperors were the direct descendants of the sun goddess, Amaterasu. The reigning Emperor Hirohito was the 124th in the direct line of descent. After the bombs were dropped on August 6 and 9 of 1945, and their surrender soon thereafter, the Japanese were allowed to keep their emperor on the throne and he was not subjected to any war crimes trial. The emperor, Hirohito, came on the throne in 1926 and continued in his position until his death in 1989. Since President Truman, in effect, accepted the conditional surrender offered by the Japanese as early as May of 1945, the question is posed, “Why then were the bombs dropped?”