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Who was the first president to assume office in the middle of a war?

Answer:
Harry Truman is the first to assume office in serious wartime. The war was not really in the middle, since the Germans in Europe surrendered in less than a month after Truman took office, but the war in the Pacific with the Japanese was still very active.
Contributor: Jphelm
First answer by ID0412788669. Last edit by Jphelm. Contributor trust: 370 [recommend contributor recommended]. Question popularity: 2 [recommend question].