Morrison was a villager in Lanark who got married in 1296 to a woman. Unfortunately, the English lord of the lands arrived during their wedding celebration and Prima Noctae was enforced, meaning that the noble lord had sexual rights over all wives on the first night of their marriage. This enraged Morrison, who tried to defend his bride and her father, but backed down after being threatened by the English troops and his wife going with the lord peacefully. Due to this, Morrison became infuriated and harbored great disdain towards the English. When the Scottish under William Wallace rebelled, he joined their forces and when they attacked the castle held by Lord Bottoms, he beat him to death with a ball-and-chain, then spitting on his corpse. He later fought at Stirling and Falkirk, where he was killed by an arrow to the chest.