On this day in 1945, at 8:16 a.m. local time, the B-29 bomber Enola Gay drops atom bomb “Little Boy” over the city of Hiroshima. The weapon had been developed through the Manhattan Project, begun in 1942. As early as 1939, scientists Albert Einstein, Leó Szilárd and Eugene Wigner had strongly urged President Roosevelt to stockpile uranium ore and further sponsor the research of physicists Enrico Fermi and others, toward the development of “extremely powerful bombs of a new type.”
By Summer 1945, such a weapon, yielding the equivalent 15,000 tons of TNT, was ready for deployment, but it was newly minted President Harry S. Truman, himself a veteran of World War I, who would give the order to fire. In so doing, it was calculated that the U.S., U.S.S.R. and Britain would save countless lives which would be lost in the heated combat of a land invasion with Japan fighting to the last man, woman and child.
Approximately 80,000 people were killed as a direct result of the atomic blast, and another 35,000 were injured; scientists speculate as many as 30,000 perished instantly and completely. Still another 60,000 would be dead by the end of the year from the effects of the fallout. 28 days after the blast, the Empire of Japan surrendered unconditionally to the U.S. and her allies.
The decision to use the potentially devastating new weapon followed the Potsdam Conference of “the big three” in Germany, months after that foe’s surrender. The Potsdam Declaration claimed that “unintelligent calculations” by Japan’s military advisers had brought the country to the “threshold of annihilation.” Hoping that the Japanese would “follow the path of reason,” the leaders outlined their terms of surrender, which included complete disarmament, occupation of certain areas, and the creation of a “responsible government.” However, it also promised that Japan would not “be enslaved as a race or destroyed as a nation.” The declaration ended by warning of “prompt and utter destruction” if Japan failed to unconditionally surrender.
News of Hiroshima’s destruction was only slowly understood in Tokyo. Many members of the Japanese government did not appreciate the power of the new Allied weapon until after the Nagasaki atomic attack of August 9. Meanwhile, on August 8, the Soviet Union had declared war against Japan. The confluence of these developments tipped the scales within the government in favor of a group that had, since the spring, been advocating a negotiated peace.
On August 10 the Japanese government issued a statement agreeing to the surrender terms of the Potsdam Declaration on the understanding that the emperor’s position as a sovereign ruler would not be prejudiced. In their reply the Allies granted Japan’s request that the emperor’s sovereign status be maintained, subject only to their supreme commander’s directives. Administration under the Supreme Commander for the Allied Powers (SCAP), Gen. Douglas MacArthur, was in the offing.
Japan accepted this proviso on August 14, and Emperor Hirohito urged his people to accept the decision to surrender. Bringing his subjects to an understanding was a difficult learning curve, and every effort was made to persuade the Japanese to accept the defeat that they had come to regard as unthinkable. Even princes of the Japanese Imperial house were dispatched to deliver the Emperor’s message in person to distant Japanese Army forces in China and in Korea, hoping thus to mitigate the shock. A clique of diehards nevertheless attempted to assassinate the new prime minister who replaced imperial architect Hideki Tojo, one Admiral Suzuki Kantarō, but by the formal surrender of September 2 aboard the USS Missouri in Tokyo Bay, the path had been smoothed.