The Stuarts (1603-1714) Elizabeth I was succeeded by her closest relative, a Stuart, King James VI of Scotland who became James I of England. He united England and Scotland for the first time in history. With James I now king of Ireland and England, as well as Scotland, it started to be difficult to maintain peace between the Catholics and Protestants. Civil War broke out in 1642 between Royalists, who supported the monarch, and Parliamentarians, led by Oliver Cromwell, who were against the absolute power held by the king and in favor of a more powerful parliament. King Charles I, who succeeded James, was executed in 1649 and later Cromwell, the leader of the parliamentary party, became head of the established republic as Lord Protector of England, Scotland and Ireland (The Act of Settlement in 1652). The Republic lasted 11 years from 1649 to 1660. After Cromwell's death, however, Monarchy was restored with King Charles II in 1660.
Charles II had to face two major catastrophes: the Plague in 1665 and the Great Fire of London in 1666. He was succeeded by his brother James II whose reign proved disastrous. In the Battle of the Boyne (1690) James II was defeated by his daughter Mary's husband, the Protestant King of Holland William of Orange, whose accession to the throne in 1688 became known as the Glorious Revolution. William III was succeeded by Queen Anne (the second daughter of James II) who was the last Stuart ruler. Under her reign the Act of Union was passed in 1707, uniting England, Wales and Scotland into a single sovereign state, the Kingdom of Great Britain, ruled by a constitutional monarch with limited powers and a more powerful Parliament.