Complex sentence: H. R. Haldeman, the chief of staff to President-elect Richard Nixon, knew Butterfield from having studied with him at the University of California, Los Angeles and invited him to take early retirement from the USAF and become Deputy Assistant to the President.
Split into simpler sentences: H. R. Haldeman, the chief of staff to President-elect Richard Nixon, knew Butterfield from having studied with him at the University of California, Los Angeles. Haldeman invited him to take early retirement from the USAF and become Deputy Assistant to the President.