"We'll have no homes left when the English garrison from the castle comes through and burns us out! And they will!"
-MacGregor to William Wallace after the uprising at Lanark.
MacGregor was a middle-aged head of the MacGregor Clan who had their home in a neighboring glen, according to Campbell. After it became known about William Wallace leading a violent overthrow of the English garrison in Lanark's and murdering the magistrate in retribution, MacGregor led a party of his clan members to offer their support to William. William had initially declined and advised them to go home until MacGregor then warned that the English would return and raze their homes as punishment. MacGregor joined Wallace in the rebellion and participated in numerous raids and ambushes on English soldiers. He was present at the Battle of Stirling and the Siege of York where he helped to push the burning battering ram into the gates. Falkirk would be the last battle that MacGregor would fight in. He was speared to death by an English soldier during the battle after Wallace was betrayed.