Hiroshima and Nagasaki

Hiroshima and Nagasaki

Atomic Bombs



Black and white photo of iconic atomic bomb mushroom cloud
The mushroom cloud from the nuclear explosion over Nagasaki rising 60,000 feet (18 km) into the air on the morning of 9 August 1945 


On 6 August 1945, the US detonated an atomic bomb over the Japanese city of Hiroshima in the first nuclear attack in history. The atomic bombings of Hiroshima and Nagasaki were partly in reaction to the U.S. casualties suffered in the Iwo Jima and Okinawa Campaigns. In a press release issued after the atomic bombing of Hiroshima, President Harry S. Truman warned Japan to surrender or “expect a rain of ruin from the air, the like of which has never been seen on this Earth.” Three days later, on 9 August, the US dropped another atomic bomb on Nagasaki, which has been the last nuclear attack to date. Between 140,000 and 240,000 people died as a direct result of these two bombings.


Learning Objectives

  • Analyze the decision to drop the atomic bombs and discuss the aftermath of World War II.


Key Terms / Key Concepts

Iwo Jima and Okinawa Campaigns: U.S. campaigns for theses Japanese-held islands near the Japanese home islands in the first half of 1945 the length and heavy casualties of each hinting at the high cost of an invasion of the Japanese home islands, which led to the decision to detonate atomic bombs over Hiroshima

atomic bombings of Hiroshima and Nagasaki:  U.S. detonation of atomic bombs over Hiroshima on 6 August 1945 and Nagasaki on 9 August 1945, which forced Japan to surrender, ended World War II, and ushered in the atomic age


The necessity of atomic bombings has long been debated, with detractors claiming that a naval blockade and incendiary bombing campaign had already made invasion and, therefore, the atomic bomb was unnecessary. However, other scholars have argued that the atomic bombings shocked the Japanese government into surrender, with the Emperor finally indicating his wish to stop the war. Another argument in favor of the atomic bombs is that they helped avoid a costly invasion, or a prolonged blockade and conventional bombing campaign, either of which would have exacted much higher casualties among Japanese civilians.

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