The decision to drop the atomic bombs on Hiroshima and Nagasaki and the Japanese surrender were both motivated more by the Soviet Union than the exigencies of warfare. Japan was on the verge of surrender anyway and was more afraid of a Soviet invasion than they were of more bombs. The U.S. was positioning itself for postwar domination; most of the military brass was against the bombings. 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.