Robert Bruce was not the only noble with a claim to the Scottish throne - his was not even the strongest.
John Comyn, once a joint Guardian of Scotland with Bruce, was more closely related to the last king of Scotland, John Balliol.
Bruce and Comyn had been trying to decide how Scotland should be ruled for some time before the winter of 1305-1306.
They had been in constant negotiations with one another and had arranged a meeting in Greyfriar's Kirk, in Dumfries on 10 February 1306.
Historians are uncertain about what actually happened at the meeting, but most agree the following:
If Bruce had killed Comyn, he had done so in a holy place. This meant that he had committed sacrilege - a crime against the Church. This demanded punishment. The Pope decided to excommunicate Bruce - banishing him from the Catholic Church.
This action would have weighed heavily on Bruce. The Church gave legitimacy and protection to kingly authority. Without its support, Bruce would find it difficult to hold on to power if he became king.