In 1660, William Douglas, the brother of the second Marquess of Douglas became, through marriage, the Duke of Hamilton. Eventually, the titles of Marquess of Douglas, Earl of Angus, and several others devolved to the Dukes of Hamilton and the heir of that house is always styled 'Marquess of Douglas and Clydesdale'. The Douglas and Hamilton lines became Douglas-Hamilton and, under Scots law, are barred from inheriting the title of chief of Clan Douglas due to the hyphenated surname. This similarly applies to the Douglas-Home family who joined their surnames in the nineteenth century.