Complex sentence: Chiperfield was appointed as a member of the House Committee on Foreign Affairs in 1939, and he served as committee chairman from 1953 to 1955 (Eighty-third Congress), losing his chairmanship when the Democrats organized the Eighty-fourth Congress.
Split into simpler sentences: Chiperfield was appointed as a member of the House Committee on Foreign Affairs in 1939. Chiperfield lost the chairmanship when the Democrats organized the Eighty-fourth Congress.