Complex sentence: He was the great-grandfather of Archibald Cox, who's mother Frances Bruen Perkins was the daughter of Edward Clifford Perkins and Elizabeth Hoar Evarts; the daughter of US Attorney General, Secretary of State and Senator William Maxwell Evarts.
Split into simpler sentences: He was the great-grandfather of Archibald Cox, who's mother Frances Bruen Perkins was the daughter of Edward Clifford Perkins and Elizabeth Hoar Evarts. Elizabeth was the daughter of US Attorney General, Secretary of State and Senator William Maxwell Evarts.