The Wars of the Three Kingdoms is the collective term for a series of conflicts fought between 1639 and 1653 in England, Scotland, and Ireland, then separate entities in a personal union under Charles I. They include the 1639 to 1640 Bishops' Wars, the First and Second English Civil Wars, the Irish Confederate Wars, the Cromwellian conquest of Ireland, and the Anglo-Scottish War of 1650–1652. They resulted in the execution of Charles I, the abolition of monarchy, and founding of the Commonwealth of England, a unitary state which controlled the British Isles until the Stuart Restoration in 1660.
Political and religious conflict between Charles I and his opponents dated to the early years of his reign. While the vast majority supported the institution of monarchy, they disagreed on who held ultimate authority. Royalists generally argued political and religious bodies were subordinate to the king, while most of their Parliamentarian opponents backed a limited form of constitutional monarchy. This was worsened by differences over religion and religious freedom. Reformed Protestants such as the English Puritans and Scottish Covenanters opposed the changes Charles tried to impose on the Protestant state churches of England and Scotland. In Ireland, the only one with a Catholic majority, the Irish Confederates wanted an end to anti-Catholic discrimination, greater self-governance, and a reversal of land grants to Protestant settlers.
The conflicts began with the Bishops' Wars of 1639–1640, when Scottish Covenanters who opposed Charles' religious reforms gained control of Scotland and briefly occupied northern England. Irish Catholics launched a rebellion in 1641, which developed into ethnic conflict with Protestant settlers. The Irish Catholic Confederation, formed to control the rebellion, held most of Ireland in the ensuing war against the Royalists, Parliamentarians, and Covenanters. Although all three agreed on the need to quell the rebellion, none trusted the other two with control of an army raised to do so. In August 1642, failure to break the resulting political deadlock sparked the First English Civil War, which pitted Royalists against both the Parliamentarians and their Covenanter allies in England and Wales.
The war in England ended when Charles surrendered to the Scots in 1646, but divisions among his opponents and his refusal to make significant political concessions caused a renewed outbreak of fighting in 1648. In the Second English Civil War, Parliamentarians again defeated the Royalists and a Covenanter faction called the Engagers. The Parliamentarian New Model Army then purged England's parliament of those who wanted to continue negotiations with the king. The resulting Rump Parliament approved his execution in January 1649 and founded the republican Commonwealth of England. In the Treaty of Breda, the Scots agreed to restore Charles II to the English throne, but were defeated in the 1650–1652 Anglo-Scottish war. Under Oliver Cromwell, the Commonwealth conquered Ireland and most Irish Catholic lands were seized. The British Isles became a united republic ruled by Cromwell and dominated by the army. There were sporadic uprisings until the monarchy was restored in 1660.
The term Wars of the Three Kingdoms first appears in A Brief Chronicle of all the Chief Actions so fatally Falling out in the three Kingdoms by James Heath, published in 1662, but historian Ian Gentles argues "there is no stable, agreed title for the events....which have been variously labelled the Great Rebellion, the Puritan Revolution, the English Civil War, the English Revolution and… the Wars of the Three Kingdoms." It is generally used by modern historians who see the conflicts in each state as driven by overlapping but often distinct issues, rather than as mere background to the English Civil War, while others have labelled them the British Civil Wars.
After 1541, monarchs of England styled their Irish territory as a Kingdom—replacing the Lordship of Ireland—and ruled there with the assistance of a separate Irish Parliament. Also, with the Laws in Wales Acts 1535 and 1542, Henry VIII integrated Wales more closely into the Kingdom of England. Scotland, the third separate kingdom, was governed by the House of Stuart.
By means of the English Reformation, King Henry VIII made himself head of the Protestant Church of England and outlawed Catholicism in England and Wales. In the course of the 16th century, Protestantism became intimately associated with national identity in England; Catholicism had come to be seen as the national enemy, particularly as it was embodied in the rivals France and Spain. Catholicism, however, remained the religion of most people in Ireland and for many Irish was an act of native resistance against the Tudor conquest of Ireland.
In the Kingdom of Scotland, the Protestant Reformation was a popular movement led by John Knox. The Scottish Parliament legislated for a national Presbyterian church—namely the Church of Scotland or the Kirk—and Mary, Queen of Scots, a Catholic, was forced to abdicate in favour of her son James VI of Scotland. James grew up under a regency disputed between Catholic and Protestant factions; when he took power, he aspired to be a "universal King", favouring the English Episcopalian system of bishops appointed by the king. In 1584, he introduced bishops into the Church of Scotland, but met with vigorous opposition, and he had to concede that the General Assembly of the Church of Scotland would continue to run the church.
The personal union of the three kingdoms under one monarch came about when King James VI of Scotland succeeded Elizabeth I to the English throne in 1603, when he also became King James I of England and of Ireland. In 1625, Charles I succeeded his father and marked three main concerns regarding England and Wales: how to fund his government, how to reform the church, and how to limit the English Parliament's interference in his rule. At that time, he showed little interest in his other two kingdoms, Scotland and Ireland.
James VI remained Protestant, taking care to maintain his hopes of succession to the English throne. He duly became James I of England in 1603 and moved to London. James concentrated on dealing with the English court and Parliament, running Scotland through written instructions to the Privy Council of Scotland and controlling the Parliament of Scotland through the Lords of the Articles. He constrained the authority of the General Assembly of the Church of Scotland and stopped it from meeting, then increased the number of bishops in the Church of Scotland. In 1618, he held a General Assembly and pushed through Five Articles of Episcopalian practices, which were widely boycotted.
After his death in 1625, James was succeeded by his son Charles I, who was crowned in Holyrood Palace, Edinburgh, in 1633, with full Anglican rites. Charles was less skillful and restrained than his father; his attempts to enforce Anglican practices in the Church of Scotland created opposition which reached a flashpoint when he introduced the Anglican Book of Common Prayer. His confrontation with the Scots came to a head in 1639, when he tried and failed to coerce Scotland by military means during the Bishops' Wars.
Charles shared his father's belief in the Divine Right of Kings, and his persistent assertion of this standard seriously disrupted relations between the Crown and the English Parliament. The Church of England remained dominant, but a powerful Puritan minority, represented by about one third of Parliament, began to assert themselves; their religious precepts had much in common with the Presbyterian Scots.
The English Parliament and the king had repeated disputes over taxation, military expenditure, and the role of the Parliament in government. While James I had held much the same opinions as his son regarding Royal Prerogatives, he usually had enough discretion and charisma to persuade Parliamentarians to accept his thinking. Charles had no such skill and, faced with multiple crises during 1639–1642, he failed to prevent his kingdoms from sliding into civil war. When Charles approached Parliament to pay for a campaign against the Scots, they refused. They then declared themselves to be permanently in session—the Long Parliament—and soon presented Charles with a long list of civil and religious grievances requiring his remedy before they would approve any new legislation.