Unenviable William Wallace Link. Sir Maurice Buchanan 10th of Buchanan married Margaret Menteith (also spelt Menteith). Margaret was the daughter of Sir Walter Menteith of Rusky, and granddaughter of Sir John of Menteth, Sheriff of Dunbarton Castle, and Helena daughter of Gartnait, Earl of Mar. Sir John is reputed to have betrayed Sir William Wallace to King Edward I of England on 5 Aug 1305. Sir John was imprisoned by king Robert I but in 1314 "through influence of his sons-in-law; Malice, Earl of Strathern; Sir Archibald Campbell, of Lochow; and Maurice Buchanan, of Buchanan, he was released immediately before the Battle of Bannockburn, where he deported himself valiantly on the part of the Scottish king." Sir John was also a signatory to the Declaration of Arbroath in 1320.