Which U.S. President served a single term during a major global conflict, was known for a policy that significantly altered the nation's role in international affairs, and had a Secretary of State who later became a prominent figure in international law?

1. His presidency was during a time of global war.
2. His foreign policy included a doctrine that bears his name.
3. His Secretary of State played a key role in the development of a major international charter.
4. He was in office during the 1940s.