When Admiral Elliott Buckmaster took command of Task Force 74 operating in the South China Seas, Ritcheson joined his staff as Signal Officer.
After the end of the war, Ritcheson returned to his studies and obtained his Bachelor of Arts degree in philosophy and classics in 1946.
In 1971–74, he served as Colin Rhys Professor of British History at the University of Southern California, and then became cultural attaché (Foreign Service Officer Grade 1) at the American Embassy, London.
Returning from his diplomatic assignment in the United Kingdom, he became Lovell Distinguished Professor, 1977–1984 and was awarded the university prize for creative scholarship.
When he retired from the University of Southern California in 1991, he became executive vice-president of the not for profit Fund for Arts and Culture in Eastern Europe from 1991 to 1996, and was country director for Hungary and subsequently Poland.
In 1997 he became executive vice president for planning for the Trust for Museum Exhibitions based in Washington, D.C. Ritcheson is a member of Phi Beta Kappa, Fellow of the Royal Historical Society, a member of the Texas Institute of Letters, the Société Française d'Archeologie, Association pour le rayonnement de l'Opéra national de Paris, Brooks's, the Beefsteak Club, London, and the Cosmos Club, Washington, D.C. Pe-Et Society (Oklahoma U.