Why the US dropped atomic bombs on Japan

On 6 August 1945 the US dropped Little Boy on Hiroshima, and three days later Fat Man on Nagasaki. Together the bombs killed an estimated 150,000–246,000 people, most of them civilians.

The stated reason

The official justification was that a conventional invasion of the Japanese home islands (Operation Downfall) would have cost hundreds of thousands of Allied lives and far more Japanese ones. The bomb, the argument went, ended the war faster and saved lives on balance.

The contested reason

Many historians (notably Gar Alperovitz) argue Japan was already seeking terms through the Soviets, and that a major motive was atomic diplomacy — demonstrating the weapon to the USSR to shape the postwar order. The two explanations aren't mutually exclusive.

Why it stayed with me

Standing at the Genbaku Dome — the one building left standing near the hypocentre, now a UNESCO site — is supposed to be one of the most sobering experiences a traveller can have. I want to see both Peace Memorial Parks in person.