Complex sentence: Cato was an African-American slave who served as an American Black Patriot spy and courier gathering Intelligence during the American Revolutionary War with his owner, Hercules Mulligan, who was a "sub-agent of the Culper Ring" in New York City.
Split into simpler sentences: Cato was an African-American slave who served as an American Patriot spy and courier during the American Revolutionary War. His owner, Hercules Mulligan, was a "sub-agent of the Culper Ring" in New York City.