After Germany's surrender in May 1945, the U.S. and its allies were able to concentrate their efforts on forcing Japan to surrender. With the fall of the Marianas Islands in July 1944, it had become apparent to military leaders on all sides that the fall of Japan was a foregone conclusion (Long). The increased capability of B29 bombers to strike Japan opened Japan's cities and industry to severe attacks. Coupled with a Naval blockade that crippled Japan's ability to gain the resources to wage war, it was only a question of when the surrender would occur. By June 1945, General Curtis LeMay estimated that U.S. airstrikes would have no Japanese targets left by October 1945 (Long). As early as June 1945, the U.S. had intercepted cables from the Japanese to the Russians seeking aid in an offer to surrender (Lewis).
With Japan weakening, the Potsdam Declaration of July 1945 called for Japan's unconditional surrender. The harsh rhetoric of the declaration, aimed at the Japanese, indicated that Emperor Hirohito would be deposed and treated as a war criminal. Due to the Japanese religious belief that the emperor was a God, the Proclamation was unacceptable even to the Japanese peace movement. While Japan attempted to negotiate surrender through Russia, the U.S. held fast demanding the complete dismantling of the Japanese authority. The fate of the emperor, and the unwillingness of the U.S. to have Russia broker the deal, were the main points impeding a calculated surrender.
Leading scientists as well as military leaders of this period overwhelmingly opposed using the new dreadful weapon. Most found its use against a civilian population repugnant. Many of them suggested a demonstration to the Japanese of its awesome capabilities in an effort to persuade them into surrender. Most agreed that a demonstration would be less than effective and a waste of a bomb. Truman writes in his private diary of July 25, 1945, that he has ordered the bomb dropped on a purely military target and spare civilians, women, and children (Truman Diary). It was clear by his diary entry that he understood the ramifications of the bomb's destructive capability.
Truman had quipped that the Japanese would fight to their last dying man and an invasion would cost a million American lives. These were anecdotal estimates and had no military basis. In fact, in the days before the bomb was dropped, Japan was trying to secure an acceptable surrender that would maintain the Emperor's fate. Yet, in the face of scientific opposition and military skepticism, Truman stuck to the order to drop the bombs and struck Hiroshima on August 6, 1945. A second strike hit Nagasaki on August 9, 1945. When the bomb was dropped, the American public shared Truman's enthusiasm laced with a hint of the gloom that rose over the horizon. The perception is still prevalent today that the bomb prevented an invasion and saved American lives (Hogan, 146).
Estimates are that 170,000 Japanese were killed instantly from the bomb and the ensuing radiation (Anhalt). Most were civilians. Still, the Japanese Cabinet refused to surrender due to their belief in the emperor as a God. As