The English Civil War (1642–1651) was a series of armed conflicts and political machinations between Parliamentarians ("Roundheads") and Royalists ("Cavaliers") over, principally, the manner of England's government. The first (1642–1646) and second (1648–1649) wars pitted the supporters of King Charles I against the supporters of the Long Parliament, while the third (1649–1651) saw fighting between supporters of King Charles II and supporters of the Rump Parliament. The war ended with the Parliamentarian victory at the Battle of Worcester on 3 September 1651.
The overall outcome of the war was threefold: the trial and execution of Charles I (1649); the exile of his son, Charles II (1651); and the replacement of English monarchy with, at first, the Commonwealth of England (1649–1653) and then the Protectorate under the personal rule of Oliver Cromwell (1653–1658) and subsequently his son Richard (1658–1659). The monopoly of the Church of England on Christian worship in England ended with the victors consolidating the established Protestant Ascendancy in Ireland. Constitutionally, the wars established the precedent that an English monarch cannot govern without Parliament's consent, although the idea of Parliament as the ruling power of England was only legally established as part of the Glorious Revolution in 1688.
The term "English Civil War" appears most often in the singular form, although historians often divide the conflict into two or three separate wars. These wars were not restricted to England as Wales was a part of the Kingdom of England and was affected accordingly, and the conflicts also involved wars with, and civil wars within, both Scotland and Ireland. The war in all these countries is known as the Wars of the Three Kingdoms.
Unlike other civil wars in England, which focused on who should rule, this war was more concerned with the manner in which the kingdoms of England, Scotland, and Ireland were governed. The 1911 Encyclopædia Britannica called the series of conflicts the "Great Rebellion", while some historians – especially Marxists such as Christopher Hill (1912–2003) – have long favoured the term "English Revolution".
The two sides had their geographical strongholds, such that minority elements were silenced or fled. The strongholds of the royalty included the countryside, the shires, and the less economically developed areas of northern and western England. On the other hand, all the cathedral cities (except York, Chester, Worcester and Hereford and the royalist stronghold of Oxford) sided with Parliament. All the industrial centers, the ports, and the economically advanced regions of southern and eastern England typically were parliamentary strongholds. Lacey Baldwin Smith says, "the words populous, rich, and rebellious seemed to go hand in hand".