Royalist. Born in Dalkeith, Campbell was a consistent supporter of the Royalist cause, fighting at Dunbar (1650) and Worcester (1651) and then imprisoned under the regime of Oliver Cromwell (1599 - 1654). After the restoration he eventually regained the Earldom which had been forfeited by his less consistent father, who had been the 1st Marquis and 8th Earl.
Campbell objected to the Test Act (1681) on the basis of continuing royal supremacy over the church and the inconsistency of its insistence on a Protestant monarch, when the heir to the throne had embraced Catholicism. He was imprisoned once again, but managed to escape to the Netherlands. When King James VII (1633 - 1701) acceded to the throne, Campbell landed in Scotland with the intention of restoring a Protestant monarchy (1685). However, like the Duke of Monmouth's simultaneous action in England, it failed and the Earl was captured and executed in Edinburgh.