Complex sentence: John Winthrop was born at Groton Manor in 1587; he became the leader of the Winthrop Fleet, a founder of the city of Boston, and one of the first Governors of the Massachusetts Bay Colony.
Split into simpler sentences: John Winthrop was born at Groton Manor in 1587. He became the leader of the Winthrop Fleet, a founder of the city of Boston and one of the first Governors of the Massachusetts Bay Colony.