How long did parliament gain power during the war?

During the English Civil War, Parliament gained significant power, particularly after the victory over the Royalists in the battle of Naseby in 1645. By the end of the war in 1651, Parliament had established itself as the primary governing body, effectively diminishing the monarchy's authority. The conflict fundamentally altered the political landscape, leading to the eventual establishment of the Commonwealth under Oliver Cromwell. Overall, the war marked a decisive shift in power from the monarchy to Parliament.