Complex sentence: He was the third African-American to graduate from Dartmouth College, and, following on the heels of John Brown Russwurm, Gibbs became the second black man in the nation to deliver a commencement address at a college.
Split into simpler sentences: He was the third African-American to graduate from Dartmouth College. And, following on the heels of John Brown Russwurm, Gibbs became the second black man in the nation to deliver a commencement address at a college.