Charles Burton Marshall, 91, a foreign policy expert who was the first Paul H. Nitze professor of international politics at Johns Hopkins University's School of Advanced International Studies, died of an intestinal infection Dec. 22 at a hospital in Portland, Ore. A former Arlington resident, he had moved to Oregon this year to be with relatives.

Dr. Marshall, a former research associate at the Washington Center for Foreign Policy Research, wrote four books on foreign policy and served on the SAIS faculty in Washington for 10 years until his retirement in 1975. He wrote "The Limits of Foreign Policy" (1954), "The Exercise of Sovereignty" (1965), "The Cold War: A Concise History" (1965), and "Crisis Over Rohdesia: A Skeptical View" (1967).

He was born in Catskill, N.Y., and raised in El Paso. As a young man, he worked as a newspaper reporter in Texas and Detroit. He graduated from the University of Texas, where he also received a master's degree in international studies. He received a doctorate in international relations and constitutional law from Harvard University in 1939.

After serving as lieutenant colonel in the Army during World War II, he joined the staff of the House Committee on Foreign Affairs and later took a job with the policy planning staff at the State Department. One of his assignments at the State Department was serving as an adviser to the prime minister of Pakistan.

He was a member of the Cosmos Club and the Washington Institute of Foreign Affairs.

His marriage to Doris Marshall ended in divorce. His second wife, Betty O'Brien Marshall, died in 1991.

Survivors include two children from his first marriage, Charles R. Marshall of Beaverton, Ore., and Jean Vickery of Chapel Hill, N.C.; four grandchildren; and three great-grandchildren.