Complex sentence: She served as United States Secretary of the Air Force between 1993 and 1997, making her the first female Secretary of the Air Force and the first woman to lead an entire branch of the U.S. military in the Department of Defense.
Split into simpler sentences: She served as United States Secretary of the Air Force between 1993 and 1997, making her the first female Secretary of the Air Force. She is the first woman to lead an entire branch of the U.S. military in the Department of Defense.