He served briefly as governor of Massachusetts (1636–37) then played a leading role in the English Long Parliament until 1660. A promoter of the Solemn League and Covenant and the Self-Denying Ordinance, from 1643 to 1653 he was the civil leader of the Parliamentary cause, while Cromwell directed the army. He opposed the trial and execution of Charles I and in 1653 disagreed with Cromwell over the expulsion of the Rump Parliament. After a period out of politics, he helped to bring about the recall of the Rump (1659). At the Restoration he was arrested and executed for treason.