George F. Kennan led a remarkable life. He was a Pulitzer Prize-winning historian and an American diplomat who had a large part in shaping American foreign policy during the early years of the Cold War. Kennan died Thursday at his home in Princeton, New Jersey at the age of 101.

Perhaps Kennan's most influential work was written anonymously in the journal 'Foreign Affairs.' In the article, written in 1947 and attributed to 'X,' Kennan spelled out what would become the American policy of containment used during the Cold War.

Kennan wrote, 'It is clear that the main element of any United States policy toward the Soviet Union must be that of a long-term, patient but firm and vigilant containment of Russian expansive tendencies.'

Containment aimed to stop the spread of communism around the world and influenced such future decisions as the founding of NATO, the Korean War, the Vietnam War, the Berlin airlift and the Cuban Missile Crisis.

Kennan worked in the Foreign Service between 1926 and 1953 and specialized in Russian history and the Soviet Union. He later served at the U.S. Embassy in Moscow.

Kennan's son-in-law, Kevin Delany said, 'He was a giant. Many people have called him the most important foreign service officer of the past half-century. He was a very thoughtful man with an elegant writing style. He wrote 20 different books, the last published in 2002, when he was 98.'

As a writer, Kennan won the Pulitzer Prize and the National Book Award for his work, 'Memoirs, 1925-1950' which was published in 1967. Among his other books were 'American Diplomacy 1900-1950,' 'Russia and the West Under Lenin and Stalin' and 'Soviet-American Relations 1917-1920.'

Former Secretary of State Henry Kissinger told the Washington Post that Kennan came 'as close to authoring the diplomatic doctrine of his era as any diplomat in our history.'

Kennan is survived by his wife, Annelise, four children, eight grandchildren and two great grandchildren.