An ambitious and daring adventurer, Beaumont was a French knight in Edward’s army. He was an experienced campaigner who fought in every major engagement against the Scots, including the battle of Falkirk. His marriage to Alice Comyn brought him a claim to lands in Scotland.
Beaumont fought with Clifford’s cavalry at Bannockburn. On 23 June, as they advanced on Stirling Castle, they encountered Randolph’s schiltron in the woods by St Ninian’s. Beaumont was keen to draw the spearmen out from the cover of the woods into the open, but this proved disastrous. The cavalry were unable to break up the tightly-formed schiltron, and were driven back in bloody confusion.
The following day, Beaumont accompanied the king on his desperate flight from the scene of defeat. In the months after Bannockburn, because he continued to side with the English, Beaumont was forced to give up his Scottish lands. Bitter, he became more determined than ever to force Bruce from the throne and continued to fight against the Scots for the rest of his life.