Complex sentence: When he retired in June 1988 he became the first African-American Coast Guard Academy graduate to retire as a regular line office from the service, and held the rank of Lieutenant Commander during his last 10 years of service.
Split into simpler sentences: When he retired in June 1988 he became the first African-American Coast Guard Academy graduate to retire as a regular line office from the service. Steverson held the rank of Lieutenant Commander during his last 10 years of service.