A Royalist general 'of most resolute and undaunted spirit', Montrose actually began his military career fighting against Charles I. In 1640 he led the Scottish Covenanting armies across the Tweed and occupied the Northeast of England. At the onset of the Civil War, he changed allegiance and raised a Royalist army in Scotland. He won a series of tactically brilliant victories, 1644–1645, but was eventually forced to join Charles II in exile. Five years later, a final attempt to defeat the Covenanters ended with his capture and execution.