Harry Truman was president of the United States from April 12, 1945 until Jan. 20, 1953. As Franklin D. Roosevelt's vice president, Truman became president when Roosevelt died.
Roosevelt's fourth term had just begun a month earlier, so Truman had almost a full term as president before the 1948 election campaign. During his first term, Truman oversaw the conclusion of World War II, including the surrender of the Nazi armies and the dropping of atomic bombs on Japan. He then transitioned America from a wartime to a peacetime economy. After a surprise win in the election of 1948, Truman wrestled with the beginning of the Cold War, sending troops to Korea when the communist North Koreans attempted to conquer South Korea. Unpopular at the end of his first full term, Truman declined to run again in 1952 and retired to his Missouri home, where he died on Dec. 26, 1972.