a war (1642-51) between the King of England, Charles I, and his parliament. Its causes were both political and religious. It divided the people of England and caused great suffering. Charles I's soldiers (the Cavaliers) were defeated by those of Parliament (the Roundheads) at the battles of Marston Moor (1644) and Naseby (1645). The Roundhead soldiers were very well organized, in the New Model Army, under Thomas Fairfax and Oliver Cromwell. Charles I was held prisoner for more than two years, and was then executed, in January 1649. The Commonwealth was declared and Oliver Cromwell ruled as 'Protector'. The Commonwealth did not last long after Cromwell's death, however, and in 1660 Charles's son took his place as King Charles II at the Restoration.