Dillon served in the US army for eighteen months before being discharged and continuing his education at Duke University.

in English Literature in 1951, he served as a CIA intelligence officer with Chinese Nationalist irregular forces.

Dillon spent more than 30 years in the Foreign Service with assignments including Venezuela, Turkey, Malaysia, Egypt, Lebanon.

[3] Dillon served as US Ambassador to Lebanon for two years, surviving the 1983 United States embassy bombing, before retiring from the foreign service in 1983 with the rank of Career Minister.

[2] After his time in the Foreign Service, Dillon joined the United Nations as Assistant Secretary General and later served for five years as Deputy Commissioner General of the United Nations Relief and Works Agency for Palestine Refugees in the Near East.