 On 24 March 1566, Queen Mary appointed him captain of Newark Castle, Selkirkshire, whereupon he supported her with a force of over 3,000 men.In January 1570 (in reliance upon the distraction likely to be caused by the assassination of the Regent Moray, of which he had advance knowledge), he engaged in depredations on the English side of the Border.By way of retaliation the English, under the Earl of Sussex and Lord Scrope, destroyed his stronghold at Branxholme Castle.