Final answer:
Truman dropped the atomic bomb to bring the war in the Pacific to a swift end.
Step-by-step explanation:
Truman's reason for dropping the atomic bomb was to bring the war in the Pacific to a swift end. The decision to drop the bombs on Hiroshima and Nagasaki was made in order to force Japan's surrender and avoid the need for a full-scale invasion of Japan, which would have cost many more lives. The bombings served as a powerful demonstration of the destructive power of the atomic bomb and convinced Japan to surrender.
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