Complex sentence: He served in the Department of State, Washington, D.C., in 1920 and 1921, and was third secretary of the American Embassy, attached to the United States High Commission, in Constantinople, 1921-1923.
Split into simpler sentences: He served in the Department of State, Washington, D.C., in 1920 and 1921. Third secretary of the American Embassy, attached to the United States High Commission, in Constantinople 1921-1923.