Complex sentence: Once Warwick became safe from external threats, Greene became active in its government, serving on the town council, being Deputy to the General Court of the colony, and serving as magistrate of the General Court of Trials.
Split into simpler sentences: Once Warwick became safe from external threats, Greene became active in its government. He served on the town council, was Deputy to the General Court of the colony, and served as magistrate of the General Court of Trials.