TURNING POINTS
Why Nagasaki Was Bombed: An Order, a Weather Window, and a Diversion
The second atomic attack grew from a standing military directive, an accelerated schedule, and a flight that could not reach its first target.
Nagasaki was not the primary target on August 9, 1945, and Truman issued no separate order after Hiroshima. The second atomic attack followed an existing directive, an accelerated weather schedule, and a diversion from Kokura.
At 3:47 a.m. on August 9, 1945, the B-29 *Bockscar* left Tinian carrying the plutonium bomb known as Fat Man. Its primary target was Kokura, not Nagasaki. [2][3]
That fact is central to understanding the second atomic attack. Nagasaki was not selected through a separate presidential decision made after Hiroshima. By the time *Bockscar* took off, the military had authority to use additional atomic bombs as they became available. A worsening weather forecast moved the mission forward, and poor visibility over Kokura sent the bomber to its alternate target.
The Order That Preceded Hiroshima
On July 25, Gen. Thomas T. Handy, acting for the Army chief of staff, sent Gen. Carl Spaatz a directive approved by Secretary of War Henry Stimson. It authorized atomic attacks on Hiroshima, Kokura, Niigata, and Nagasaki. [1]
The directive did not authorize only one strike. It stated that “additional bombs will be delivered” against the listed targets as soon as they were ready. [1] Manhattan Project planning anticipated continued bomb shipments during August. [6]
President Harry S. Truman did not issue a separate order specifically directing the bombing of Nagasaki after Hiroshima was attacked on August 6. Nor did the administration hold high-level meetings between August 6 and 9 to decide whether to use the second bomb. [4]
The second mission was therefore part of an existing operational plan. Its timing still depended on practical matters: a ready weapon, a crew and aircraft, and weather over the target.
A Mission Moved Ahead of Bad Weather
Fat Man had initially been scheduled for August 11. On August 7, planners at Tinian moved the mission to August 9 because forecasts called for adverse weather. [2]
Over Kokura, Maj. Charles W. Sweeney and the *Bockscar* crew made three unsuccessful bombing runs. Clouds and smoke prevented the visual conditions required for the attack, while the aircraft’s fuel situation became more pressing. [3]
Sweeney then turned to Nagasaki, the alternate target. Nagasaki was an industrial port city with major Mitsubishi manufacturing facilities, but it had not been the first destination that morning. [2]
Fat Man detonated over Nagasaki’s Urakami Valley at 11:02 a.m. on August 9. An estimated 40,000 to 75,000 people were killed immediately. [3] After releasing the bomb, *Bockscar* landed at Okinawa with little fuel remaining. [3]
The sequence does not reduce American responsibility for the attack. It shows, instead, how a prior directive, an accelerated schedule, and conditions over Kokura determined where the bomb was dropped.
Japan’s Crisis—and Truman’s Intervention
The Nagasaki attack came on the same day that the Soviet Union declared war on Japan and began its invasion of Japanese-held Manchuria. Japan’s leaders faced both developments amid the wider pressure of blockade, conventional bombing, military defeat, and the prospect of invasion.
Historians continue to debate the relative influence of the atomic bombings and Soviet entry into the war on Japan’s decision to surrender. The evidence does not support reducing that decision to a single cause.
Nagasaki also changed the American command arrangement. On August 10, Gen. Leslie Groves told Gen. George C. Marshall that another bomb could be ready around August 17 or 18. [5] Truman then ordered that no further atomic bomb be used against Japan without his explicit authorization, and Marshall recorded the instruction. [5]
That order did not undo the attacks on Hiroshima and Nagasaki. It did end the open-ended operating arrangement under which the second mission had proceeded. Further use of the weapon now required direct presidential approval.
Frequently Asked Questions
Did Truman order the bombing of Nagasaki?
Truman did not issue a separate order directing the August 9 attack after Hiroshima. Nagasaki was struck under the July 25 directive authorizing attacks on listed targets and additional bomb deliveries as weapons became ready. [1][4]
Why was Nagasaki bombed instead of Kokura?
Kokura was the primary target. After three unsuccessful runs in poor visibility, *Bockscar* diverted to Nagasaki, its alternate target. [2][3]
When did Truman stop further atomic attacks?
On August 10, 1945, Truman ordered that no further atomic bomb be used against Japan without his explicit authorization. [5]
TIMELINE
Key moments
Sources
- Manhattan Project: Order to Drop the Atomic Bomb — U.S. Department of Energy, Office of Scientific and Technical Information
- The Bombing of Nagasaki, August 9, 1945 — The National WWII Museum
- Manhattan Project: The Atomic Bombing of Nagasaki, August 9, 1945 — U.S. Department of Energy, Office of Scientific and Technical Information
- The Atomic Bombing of Nagasaki — University of North Carolina Press Blog
- Gen. Marshall and Gen. Groves, August 1945 — George C. Marshall Foundation
- Memorandum from Groves for Army Chief of Staff, 'Plan of Operations – Atomic Fission Bomb,' 24 July 1945 — National Security Archive, The George Washington University
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