In 1940 Stettinius's earlier business-government liaison work on New Deal industrial recovery programs brought him the position of chairman of the War Resources Board. The following year he became director of priorities in the Office of Production Management, where he encouraged the development of synthetic rubber. In 1942 President Franklin D. Roosevelt appointed Stettinius administrator of the Lend-Lease Administration, whose organization he streamlined and rationalized while successfully winning congressional support for its sometimes controversial aid programs to the Allies.
In September 1943 Stettinius became undersecretary of state, working under Secretary Cordell Hull with a commission to improve and coordinate the State Department's notoriously inefficient structural organization and improve its lackluster public image. Stettinius's other major responsibility was the creation of an international security organization, the UN. After laying the groundwork for this in discussions with British Foreign Office counterparts in the spring of 1944, Stettinius attended the August 1944 Dumbarton Oaks conference, where he played a major role in drafting the UN Charter.
When poor health caused Hull's resignation in November 1944, Stettinius succeeded him. The new secretary instituted public relations policies that greatly enhanced his department's popularity. He attended the controversial February 1945 Yalta Conference of Allied leaders, helping to draft American proposals for a Declaration on Liberated Europe and further clarifications of the UN Charter. Stettinius's greatest diplomatic contributions occurred from April to June 1945 at the San Francisco Conference of Allied Nations, which drafted the final UN Charter. His diplomatic skills were instrumental in persuading the numerous delegates to reach consensus on a charter that all could support.
Many officials considered Stettinius a lightweight. During the San Francisco Conference, President Harry S. Truman, who succeeded Roosevelt in April 1945, decided to replace Stettinius with South Carolina Democrat James F. Byrnes. On 27 June 1945, one day after the conference ended, Stettinius resigned to become the first U.S. representative to the new UN.
Disillusioned with the Truman administration's failure to use UN mechanisms to resolve the developing Cold War, in June 1946 Stettinius left the organization and became rector of the University of Virginia. In 1949 he published a carefully documented account of the Yalta Conference, defending Roosevelt's decisions there. Stettinius died of a heart attack in Greenwich, Connecticut, on 31 October 1949.
Schlesinger, Stephen C. Act of Creation: The Founding of the United Nations; A Story of Superpowers, Secret Agents, Wartime Allies and Enemies, and Their Quest for a Peaceful World. Boulder, CO: Westview, 2003.; Stettinius, Edward R. Lend-lease, Weapon for Victory. New York: Macmillan, 1944.; Stettinius, Edward R. Roosevelt and the Russians: The Yalta Conference. Edited by Walter Johnson. Garden City, NY: Doubleday, 1949.; Walker, Richard, and George Curry. The American Secretaries of State and Their Diplomacy, Vol. 14, E. R. Stettinius, Jr., and James F. Byrnes. New York: Cooper Square, 1965.