In many respects Morton was an energetic and capable ruler. His first achievement was the conclusion of the civil war in Scotland against the supporters of the exiled Mary, Queen of Scots. In February 1573 he effected a pacification with George Gordon, 5th Earl of Huntly, the Hamiltons, and other Catholic nobles who supported Mary at Perth, with the aid of Elizabeth's envoy, Henry Killigrew. Edinburgh Castle still held out for Mary under the command of William Kirkcaldy of Grange and William Maitland of Lethington, and after a long siege the castle was taken on 27 May 1573, aided by English artillery and soldiers which finally arrived under William Drury.