The Anglo-Scottish war (1650–1652), also known as the Third Civil War, was the final conflict in the Wars of the Three Kingdoms, a series of armed conflicts and political machinations between shifting alliances of religious and political factions in England, Scotland and Ireland.
The 1650 English invasion of Scotland was a pre-emptive military incursion by the English Commonwealth's New Model Army, intended to allay the risk of Charles II invading England with a Scottish army. The First and Second English Civil Wars, in which English Royalists, loyal to Charles I, fought Parliamentarians for control of the country, took place between 1642 and 1648. When the Royalists were defeated for the second time the English government, exasperated by the duplicity of Charles I during negotiations, set up a High Court of Justice which found the King guilty of treason and executed him on 30 January 1649. At the time, England and Scotland were separate independent kingdoms, joined politically through a personal union; Charles I was, separately, both the King of Scotland, and the King of England. The Scots had fought in support of the English Parliamentarians in the First English Civil War, but sent an army in support of Charles I into England during the Second English Civil War. The Parliament of Scotland, which had not been consulted before the execution, declared his son, Charles II, King of Britain.