Scottish Protestant leader who was executed for his opposition to the Roman Catholic James II of Great Britain and Ireland (James VII of Scotland).

In his youth Campbell studied abroad but returned to Scotland in 1649. He fought at Dunbar (Sept. 3, 1650) and, after the Battle of Worcester, joined the Royalist leader Glencairn in the Highlands. Ultimately he fell foul of both the Royalists and their opponents; he was imprisoned in 1657 during the Commonwealth for refusing to renounce allegiance to the Stuarts and again in 1661 for incautious criticisms of the government of Charles II. He was released in 1663, and his father's earldom and lands were restored to him. However, his staunch Protestantism and great territorial influence made him suspect to James, Duke of York (the future James II), who became high commissioner in Scotland in 1680. He was sentenced to death on a dubious charge of high treason in 1681 but escaped to Holland and there joined the conspiracy to procure the succession of the Duke of Monmouth. He led an unsuccessful invasion of Scotland in 1685, was captured at Inchinnan on the River Clyde on June 18, and was beheaded at Edinburgh on June 30.