Nagasaki was destroyed by a plutonium atomic bomb seventy five years ago, on August 9, 1945. Called “Fat Man,” it was the same design that had been tested in the New Mexico desert less than a month before, spreading intense radioactive fallout over a wide area. A day before, on August 8, 1945, the Soviet Union had declared war on Japan, having been neutral until then. Japanese wartime leaders had been divided about surrender for weeks; now, facing a two-front war, the debate became more urgent and intense.

Susan Southard’s account of the debate in the Japanese councils of war notes that “the news of the second atomic bombing bombing had no apparent impact on their deliberations [on August 9], which, according to notes from their meeting continued throughout the day and with no further mention of Nagasaki.” The specter of occupation by the Soviets and the hopelessness of the two-front war seem to have decided the Emperor of Japan that very night to signal a surrender to the United States, which duly happened on August 15, 1945.

This much seems well-supported by the facts; despite that the controversy rages. What is even less debated is the timing of the use of the bombs and the targeting of Japan. In a blog post three days ago, I recounted, once again, that the decision to not target Germany and, instead, to orient the bomb to the Pacific theater had been taken on May 5, 1943, more than two years before Hiroshima and Nagasaki were destroyed.

The bombs were used as soon as they were ready and the weather permitted — August 6 and 9. On August 9, Nagasaki was not even the intended target; it was Kokura, but there were too many clouds over that city. So Nagasaki, a secondary target that had already been bombed with more mundane explosives, had the atomic misfortune instead. The main targets were cities that had deliberately been spared conventional bombing; the object was to measure the impact of the atomic bomb with as much scientific precision as possible. Prior destruction would confound those measurements.

The rush was not related to the anticipated large loss of lives of U.S. troops in an invasion (tens of thousands in the military’s estimates from June 1945) because that D-day was not until November 1, nearly three months after the atomic bombings. President Truman, General Marshall, and other military leaders believed that a Soviet entry into the war would cause Japan to capitulate. At the mid-July Potsdam conference, the Soviets had agreed to declare war on Japan on August 15. Following the Hiroshima bombing, Stalin accelerated that declaration by a week. He got the message the U.S. sent about the shape of the post-war world; he was going to have his say.

Why not wait till a few days after August 15 to bomb Hiroshima? Why not wait for a few days after August 8, when the Soviets actually entered the war, to use the second bomb? Why persist in the hurried schedule?

Two principal reasons can explain the rush: one imperative was to justify the use of vast resources on the Manhattan Project. If the bombs were not used and shown to be important, even decisive, in ending the war, there would be endless investigations. President Truman, as as a senator in 1944, had already threatened investigations when he was frustrated in his attempts to find out where all the money was going. Jimmy Byrnes, FDR’s director of the War Mobilization Board (and later Truman’s Secretary of State), had warned in February 1945 that he, FDR, had better show the money spent on the project was actually contributing to the war effort.

The Manhattan Project had had very high priority on wartime resources; for example, welders were sent from shipyards in San Francisco to Hanford to build the plutonium production plants there. Were the bombs not used, there could well be a reasonable argument that the Project actually cost the lives of U.S. soldiers and sailors.

The second was to announce the shape of the post-war world, most of all to the Soviet Union. Groves frankly acknowledged that when he said after the war: “There was never from about two weeks from the time I took charge of this Project any illusion my part that Russia was our enemy, and the project was conducted on that basis. I didn’t go along with the attitude of the country as a whole that Russia was a gallant ally….Of course, that was so reported to the President.” (as quoted by Martin Sherwin, in his book A World Destroyed, p. 62, Vintage Books, ppbk., 1987).

The United States and Britain had kept the fact of the bomb project from their Soviet wartime ally. Churchill had explicitly spurned a plea from the great Danish physicist Niels Bohr in 1944 that the Soviets, as allies, should be informed. In any case, Stalin was well-informed; he already knew of the bomb project through his spy network. With Truman’s hint at Potsdam about the successful atom bomb test, Stalin accelerated the Soviet bomb effort. With Hiroshima, he accelerated the Soviet declaration of war in Japan. He would have his say.

The die was cast. Having been started, at the instance of Einstein and others, as an effort to deter Hitler from blackmailing the world with atom bombs, over time it ceased being about Germany – most definitively so by early December 1944, by which time the Manhattan Project spy mission, Alsos, determined that Germany did not have a viable bomb project

At that point, the vast plutonium separation plants at Hanford Washington, operated by DuPont, had not yet been started. None of the tens of millions of gallons highly radioactive waste from plutonium separation that still haunt Eastern Washington State, had been created. At that moment, when the bomb project was accelerated instead of being stopped (a logical step had it still been about the Nazis), it had definitively become about money and power — wartime money and postwar power. That is the secret in open view about the timing of the bombing of Hiroshima and, even more so, about destruction of Nagasaki 75 years ago.

PS: Many years ago, I had the privilege of interviewing Walter Hooke, a marine veteran who was among the US troops that occupied Nagasaki. And here is my Hiroshima blog post from three days ago. These are vignettes of the history. For an overview, please refer to my 2012 talk in Santa Fe, From Pearl Harbor to Hiroshima; it’s about one hour.