Complex sentence: From 1974 to 1978 he served as Chief of Staff of the United States Air Force, and Chairman of the Joint Chiefs of Staff from 1978 until he retired from military service in 1982.
Split into simpler sentences: From 1974 to 1978, he served on the Joint Chiefs of Staff as Chief of Staff of the U.S. Air Force. In 1978, he was elevated to Chairman of the Joint Chiefs of Staff, serving until his retirement from military service in 1982.