Early in 1306 he met Comyn, the Lord of Badenoch, to whose treachery he attributed the disclosure of his plans, in the church of the Grey Friars at Dumfries, and after the interchange of a few hot words struck him with his dagger to the ground.

It was an outrage that admitted of no forgiveness, and Bruce for very safety was forced to assume the crown six weeks after in the Abbey of Scone.

The news roused Scotland again to arms, and summoned Edward to a fresh contest with his unconquerable foe.
But the murder of Comyn had changed the king's mood to a terrible pitilessness.

He threatened death against all concerned in the outrage, and exposed the Countess of Buchan, who had set the crown on Bruce's head, in a cage or open chamber built for the purpose in one of the towers of Berwick.
At the solemn feast which celebrated his son's knighthood Edward vowed on the swan which formed the chief dish at the banquet to devote the rest of his days to exact vengeance from the murderer himself.

But even at the moment of the vow Bruce was already flying for his life to the western islands.