Atomic bombings of Hiroshima and Nagasaki — 1945 use of nuclear weapons against Japan in World War II
The only use of nuclear weapons in armed conflict, killing up to 246,000 people and shaping Cold War geopolitics and nuclear deterrence doctrine.
Key Facts
- Date of Hiroshima bombing
- 6 August 1945
- Date of Nagasaki bombing
- 9 August 1945
- Total estimated deaths
- 150,000 to 246,000 people
- Hiroshima casualties
- 90,000 to 166,000 people
- Nagasaki casualties
- 60,000 to 80,000 people
- Japan's formal surrender
- 2 September 1945
By the Numbers
Location
Cause → Event → Consequence
In the final stages of World War II, Allied planners anticipated a costly invasion of the Japanese mainland. Germany had already surrendered in May 1945, and by July the Manhattan Project had produced two atomic bombs. Japan rejected the Potsdam Declaration's ultimatum for unconditional surrender, leaving Allied leadership to authorize the use of nuclear weapons against Japanese urban and military targets.
On 6 August 1945, a uranium 'Little Boy' bomb was dropped on Hiroshima by a B-29 Superfortress of the 509th Composite Group. Three days later, a plutonium 'Fat Man' bomb was dropped on Nagasaki. The blasts and their immediate and prolonged effects killed between 150,000 and 246,000 people, the majority of them civilians, in the first and only wartime use of nuclear weapons.
Japan announced its surrender on 15 August 1945 and signed a formal instrument of surrender on 2 September, ending World War II. The bombings accelerated nuclear arms development among major powers and initiated decades of Cold War deterrence policy. Ongoing debate over their ethical and legal justification has shaped international law, nuclear non-proliferation efforts, and global popular memory of atomic warfare.
Belligerents & Mobilization Analysis
Side A
2 belligerents
Thomas T. Handy.
Side B
1 belligerent