The defeat of Germany in May 1945 did not end the Second World War: bitter fighting continued against Japan in the Pacific. American commanders estimated that a full invasion of the Japanese home islands could cost vast numbers of Allied and Japanese lives.

The Manhattan Project

For years the USA had secretly developed an atomic bomb in the Manhattan Project. When the weapon was successfully tested in July 1945, President Truman faced a momentous decision.

Hiroshima and Nagasaki

On 6 August 1945 the bomb known as "Little Boy" destroyed Hiroshima. When Japan did not immediately surrender, a second bomb destroyed Nagasaki on 9 August. Together the bombs killed well over 100,000 people, many instantly and others slowly from radiation sickness. On 15 August Japan surrendered.

Debate and Consequences

Historians still argue fiercely about the decision. Supporters say it forced a rapid surrender and avoided an even bloodier invasion. Critics argue that Japan was already close to defeat, that targeting civilians was immoral, and that the bombs were partly a warning to the Soviet Union. Either way, the bombs opened the nuclear age and helped set the stage for the arms race of the Cold War.

Year 9 Democracy and Dictatorship

The Atomic Bombs on Japan