While the debate over whether America was right to use nuclear weapons in 1945 rages on, says Ward Wilson in Foreign Policy, most people agree that the bomb had its intended effect: forcing Tokyo to surrender. But that may be a myth. Japan’s Supreme Council – an “inner cabinet” of six top leaders – agreed to unconditional surrender on 9 August, three days after Hiroshima and before they’d even heard about Nagasaki. They knew Hiroshima had been hit by a devastating new weapon, killing a third of its population and destroying two thirds of the city. But those figures were nothing out of the ordinary. Over that summer, conventional American bombers had already effectively levelled no fewer than 66 Japanese cities. When the foreign minister asked the Supreme Council to discuss the bombing two days after it had happened, his fellow members declined.
So what did cause the Japanese to surrender? “Simple: the Soviet Union.” Tokyo, knowing the war was lost, had two long-shot plans for securing better surrender terms: the first was to convince Moscow to mediate a settlement with Washington; the second was to inflict such high casualties on invading US forces that Washington would improve its terms. But on 9 August, at one minute past midnight, the Soviets attacked the Japanese territory of Manchuria. In a stroke, Tokyo’s two options “evaporated”. The Supreme Council knew the Soviets could no longer act as mediators, and that Japan couldn’t “fight off two great powers” simultaneously. Within hours, they had agreed to surrender.
Five Myths About Nuclear Weapons, from which this piece is adapted, is available to buy here.