 During World War II, Hapgood was employed by the Office of the Coordinator of Information (COI, which became the Office of Strategic Services in 1942) and the Red Cross, and also served as a liaison officer between the White House and the Office of the Secretary of the War.After the war, Hapgood taught at Keystone College (1945–1947), Springfield College (1947–1952), Keene State College (1956–1966), and New England College (1966–1967), lecturing in world and American history, anthropology, economics, and the history of science.Hapgood married Tamsin Hughes in 1941 but divorced in 1955.