The Douglases became so powerful that by the early fifteenth century they were seen as a threat to the stability of the nation. In 1440 the young William Douglas, 6th Earl of Douglas and his brother were invited to dine with the ten year-old King James II of Scotland. The dinner was organised by Sir William Crichton of Clan Crichton. Known as the Black Dinner, a black bull's head, the symbol of death, was brought in. After the dinner the Douglas chiefs were dragged out to Castle Hill, given a mock trial and beheaded. The Clan Douglas then laid siege to Edinburgh Castle. Perceiving the danger, Crichton surrendered the castle to the king who was then given the title of Lord Crichton. It is still unclear exactly who else was ultimately responsible, though it is thought Livingstone and Buchan were also likely candidates.