But it's been partial hindsight, at best, and new evidence suggests the atomic bombs played less of a role in ending the war than previously thought.
Make no mistake: The whammy of two atomic bombs within a week certainly helped along Japan's surrender. But Soviet archives -- once sealed tight, now open to Russian historians -- show the Japanese were also afraid the Soviets were going to invade Manchuria and occupy parts of Japan.
"I think the Soviet presence was crucial," said Tsuyoshi Hasegawa, a professor of history at the University of California-Santa Barbara, and author of "Racing the Enemy: Stalin, Truman and the Surrender of Japan."
Hasegawa, whose specialty is Russian history, said histories for the last half-century have treated the Soviet entry into the war against Japan on Aug. 8 as a sideshow. U.S. textbooks today emphasize the use of the atomic bomb on Hiroshima on Aug. 6 and the bombing of Nagasaki on Aug. 9 as the decisive action forcing the Japanese to surrender by Aug. 14.
But Hasegawa said the bombing of Hiroshima didn't deliver a knockout punch, and the bombing of Nagasaki got surprisingly little notice at the highest levels of the Japanese government, which already was trying to find a way to end the war.
"Of course it had an impact, but it was not that decisive," said Hasegawa, who studied imperial Japanese war records in Tokyo as well as Soviet archives. "What it did was to inject urgency into Japanese diplomatic efforts to end the war."
In 1945, a woman we know, Akiko Hirata, was 18 and living with her family in Hokkaido. She knew the war was going badly for Japan; even though the radio proclaimed great victories at sea, she noticed that the young men in her town went away to fight and never returned.
Akiko Hirata later married an American, moved to the United States, became a citizen and had three children, among them the chief typist for CHATTER. For purely selfish reasons, we're glad the Soviets never got the chance to invade Hokkaido.