A high-ranking nobleman from East Lothian, Keith was the hereditary marshal of Scotland, a ceremonial role that had once involved looking after the king's horses.
He was captured by the English in 1300, but by 1308 he was back in Scotland and supporting Bruce.
Keith commanded a small Scottish cavalry force. Along with Douglas, he was given the crucial role of checking out the size and state of the English army as they advanced.
They did not have the strength or numbers to face the English cavalry but on 24 June, in a crucial move, they charged at the enemy archers, scattering them and preventing them from having an impact on the tightly-packed Scottish spearmen.
Keith was rewarded with land in the north-east of Scotland, where his family subsequently built the mighty Dunottar Castle. Ever-loyal, he became one of the king's regular courtiers and his seal is on the Declaration of Arbroath. He continued to serve Bruce’s infant son David II even after King Robert's death.