Final answer:
Colin Powell was the first African-American to be Chairman of the Joint Chiefs of Staff and Secretary of State, serving in top military and diplomatic positions.
Step-by-step explanation:
The first African-American to serve as the Chairman of the Joint Chiefs of Staff and later as the first African-American Secretary of State was Colin Powell. Colin Powell served as Chairman from October 1, 1989, to September 30, 1993, under Presidents George H. W. Bush and Bill Clinton. He was then appointed as Secretary of State by President George W. Bush, serving from 2001 to 2005. His distinguished career broke significant racial barriers in U.S. military and diplomatic history.