A knight from south-east Scotland who had sided with King Edward for many years, Seton started the battle on the side of the English, but finished it on Bruce’s side.
On the night after 23 June, Seton slipped away from the demoralised English army and made his way to Bruce’s camp. He told Bruce of the low spirits and dissatisfaction in the English camp and urged Bruce to challenge Edward again. This crucial piece of information was the final prompting Bruce needed. He made up his mind to do the unthinkable, and decided to take the English on in full battle the next day. In a rousing speech, Bruce called upon his men to join him.
Seton remained a supporter of Bruce in the years after Bannockburn and served with Edward Bruce in the Irish campaigns of 1315-1318.