Harry S. Truman (1884-1972) became the 33rd President of the United States upon the death of Franklin D. Roosevelt in April 1945. Truman, who had only a high-school education and had been vice president for just 82 days before FDR's sudden death, inherited the monumental task of leading the United States through the end of World War II and the beginning of the Cold War. Truman—who was, while in office, one of the least popular presidents in modern American history—won a surprising second term by defeating Republican Thomas Dewey in the election of 1948. Many historians today rate Truman's performance much more positively than did his constituents at the time.
Truman served as president of the United States and, therefore, Commander in Chief of the United States military during the final months of World War II. Under his command, the U.S. dropped two atomic bombs—the first to be used in warfare—on Hiroshima and Nagasaki, Japan, effectively ending the war. For many Americans, Truman's legacy as the nation's leader centers on these controversial decisions.