The Parliament was initially led by John Pym. In August 1641, it enacted legislation depriving Charles of the powers that he had assumed since his accession. The reforms were designed to rule out Charles ruling absolutely again. The parliament also freed those imprisoned by the Star Chamber. A Triennial Act was passed, requiring that no more than three years should elapse between sessions of Parliament.
The Long Parliament was also responsible for the impeachment and subsequent execution of the king's advisers, Archbishop William Laud and Thomas Wentworth, Earl of Strafford. Without its royalist members, the Long Parliament continued to sit during the Civil War. This was because its dissolution was only possible with its own consent.
Divisions emerged between various factions, culminating in Pride's Purge (1648), when, under the orders of Oliver Cromwell, Colonel Pride physically barred a Presbyterian majority of Parliament from taking their seats. In the wake of the ejections, the remnant, the Rump Parliament, arranged for the trial and execution of Charles I. It was also responsible for the setting up of the Commonwealth of England (1649).
Oliver Cromwell forcibly disbanded the Rump Parliament in 1653 when it seemed they might disband his expensive army (50,000 men). It was recalled after his son, Richard Cromwell's, dismal failure as Lord Protector in 1659. The following year General George Monck reinstated the members 'secluded' by Pride. The Convention Parliament was prepared for, and the Long Parliament dissolved in March 16, 1660..