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war1945

Fat Man — American nuclear bomb

August 9, 1945

The Fat Man bomb dropped on Nagasaki on 9 August 1945 was the most powerful nuclear weapon ever used in warfare, killing tens of thousands instantly.

Quick Facts

Year
1945
Category
war

Key Facts

Date detonated
9 August 1945
Weapon type
Implosion-type plutonium bomb
Delivery aircraft
Boeing B-29 Superfortress Bockscar
Pilot
Major Charles Sweeney
Nuclear detonation sequence
Third nuclear explosion in history
Plutonium source
Hanford Site, manufactured at Los Alamos

Location

Map of Nagasaki, JapanMap of Nagasaki, JapanNagasaki, Japan

Cause → Event → Consequence

Cause

The United States, seeking to compel Japan's surrender and end World War II in the Pacific without a costly land invasion, developed plutonium-based implosion devices at Los Alamos Laboratory. Following the Trinity test in July 1945 and the uranium bomb dropped on Hiroshima on 6 August, the military proceeded with a second atomic strike using a Fat Man device.

Event

On 9 August 1945, a Fat Man implosion-type nuclear bomb with a solid plutonium core was dropped from the B-29 Bockscar, piloted by Major Charles Sweeney, and detonated over Nagasaki, Japan. It was the second nuclear weapon ever used in combat and the most powerful nuclear device to be employed in warfare.

Consequence

The destruction of Nagasaki, combined with the earlier Hiroshima bombing and Soviet entry into the Pacific war, contributed directly to Japan's announcement of surrender on 15 August 1945. The Fat Man design subsequently informed further nuclear tests, including Operation Crossroads in 1946 and Operation Sandstone in 1948, before being superseded by the Mark 4 nuclear bomb.

Belligerents & Mobilization Analysis

Side A

1 belligerent

United States
Key Commanders

Major Charles Sweeney.

Side B

1 belligerent

Japan
Outcome
Nagasaki destroyed; Japan surrendered, ending World War II in the Pacific

Timeline Context

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