my daily reports for the previous two weeks here and yesterday here. I've written three books on the subject: Hiroshima in America (with Robert Jay Lifton), Atomic Cover-Up (on the decades-long suppression of shocking film shot in the atomic cities by the U.S. military), and Hollywood Bomb (the wild story of how an MGM 1947 drama was censored by the military and Truman himself).
July 27, 1945: Truman continued to meet with Allied leaders in Germany, the Soviets got ready to declare war on Japan (“fini Japs” when that happened, even without the bomb, Truman had written in his diary), and preparations to get the first A-bomb ready for use were finalized. The Japanese government released an edited version of the “unconditonal surrender” Potsdam declaration to their press and citizens, but had not yet rejected it. The Domei news agency had already predicted that the surrender demand “would be ignored.” The U.S., after use of bomb, would accept conditional surrender--with Japan allowed to keep its emperor.
Eleven days after the first, and quite secret, atomic test at Trinity, which spread wide clouds of radioactive fallout over residents downwind—livestock had been sickened or killed—radiation experts had become concerned about the exposure for one family, the shape of things to come.
“A Petition to the President of the United States” organized by famed nuclear scientist Leo Szilard, and signed by sixty-eight of his Los Alamos colleagues, urgently urging delay or extreme caution on the use of the new weapon against Japan, continued to be held in limbo and kept from the President while Truman remained abroad.
July 26, 1945: Early this day, Chief of Staff Gen.George Marshall cabled to Gen. Leslie Groves, military chief of the Manhattan Project back in Washington, DC, his approval of a directive sent by Groves the night before. It read: “1. The 509th Composite Group, Twentieth Air Force, will deliver its first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets: Hiroshima, Kokura, Niigata and Nagasaki…. 2. Additional bombs will be delivered on the above tagets as soon as made ready by the project staff…..”
This assembly-line approach would have tragic consequences for the city of Nagasaki.
In a 1946 letter to Stimson, Truman reminded him that he had ordered the bombs used against cities engaged “exclusively” in war work. Truman would later write in his memoirs, “With this order the the wheels were set in motion for the first use of an atomic weapon against a military target.” As noted yesterday, Hiroshima and Nagasaki were far from being merely "military" targets.
The other major event from this day was equally significant. The Potsdam Declaration was issued in Germany by the United States, Britain and China. (The Soviet Union was still ostensibly not at war with Japan but agreed to enter the conflict around August 7. This has led some to suggest that we used the bombs quickly to try to end the war before the Russians could claim much new territory.)
The declaration ordered Japan to surrender immediately and unconditionally or face a reign of ruin—“prompt and utter destruction”—although the new weapon was not mentioned (such a warning had been considered by Truman but rejected).
Much was made of the importance of the “unconditional” aspect but three weeks later, after the use of the new bombs, we accepted a major condition, allowing the Japanese to keep their emperor, and still called the surrender “unconditonal.” Some historians believe that if we had agreed to that condition earlier Japan might have started the surrender process before the use of the atomic bombs. Others believe an explicit warning to the Japanese, or a demonstration of the new weapon offshore in Japan, would have speeded the surrender process. But the Potsdam Declaration set US policy in stone.