The Earl of Douglas was trying to consolidate the power which he had gained through the murder of his cousins at the "Black Dinner" at Edinburgh Castle, sanctioned by the king and his own father James the Gross, 7th Earl of Douglas.
The Earl of Douglas was trying to expand his influence, which he had gained through the elimination of his relatives at the "Black Dinner" at Edinburgh Castle, approved by the king and his own father, James the Gross, 7th Earl of Douglas.