From 1947 to 1949, McDowell was information and education officer for the Eighth U.S. Army and later the 82nd Airborne Division. From 1955 to 1958 he was a professor of Russian language, history, economics, geography, and political science in a classified joint military/civilian intelligence agency and chief of the research division from 1956 to 1958. In 1959, McDowell was an instructor for the Command and General Staff College in Taiwan, Japan, Korea, and Hawaii, where he taught U.S. military forces about nuclear weapons.