Harry S. Truman (May 8, 1884 – December 26, 1972) is the 33rd President of the United States (1945–1953).

The final running mate of President Franklin D. Roosevelt in 1944, Truman succeeds to the presidency on April 12, 1945, when Roosevelt dies after months of declining health.

Under Truman, the U.S. successfully concludes the Second World War; in the aftermath of the conflict, tensions with the Soviet Union increase, marking the start of the Cold War.

Truman was born in Missouri, and spends most of his youth on his family's farm.

During the First World War, Truman serves in combat in France as an artillery officer in his National Guard unit.

After the war, he briefly owns a haberdashery and joins the Democratic Party political machine of Tom Pendergast in Kansas City, Missouri.

He is first elected to public office as a county official, and in 1934 becomes U.S. senator.

He gains national prominence as head of the wartime Truman Committee, which exposes waste, fraud, and corruption in wartime contracts.

While Germany surrenders a few weeks after Truman assumes the Presidency, the war with Japan is expected to last another year or more.

Truman's decision to use atomic weapons against Japan leads to a speedy end of the war but remains controversial.

His presidency is a turning point in foreign affairs, as the nation supports an internationalist foreign policy in conjunction with European allies.

Working closely with Congress, Truman assists in the founding of the United Nations, issued the Truman Doctrine to contain communism, and passes the $13 billion Marshall Plan to rebuild Europe, including the Axis Powers of both World Wars, whereas the wartime Ally Soviet Union becomes the peacetime enemy, and the Cold War begins.

He oversees the Berlin Airlift in 1948 and the creation of NATO in 1949.

When communist North Korea invades South Korea in 1950, he immediately sends in U.S. troops and gains UN approval for the Korean War.

After initial success, the UN forces are thrown back by Chinese intervention and the conflict is stalemated through the final years of Truman's presidency.

Corruption in Truman's administration, which is linked to certain members in the cabinet and senior White House staff, is a central issue in the 1952 presidential campaign which Adlai Stevenson, Truman's successor as Democratic nominee, loses to Republican Dwight D. Eisenhower.

Popular and scholarly assessments of his presidency are initially negative, but eventually become more positive after his retirement from politics.

Truman's 1948 election upset for his full term as president is routinely invoked by underdog candidates.