Edward I of England
The years 1264–1267 saw the conflict known as the Second Barons' War, in which baronial forces led by Simon de Montfort fought against those who remained loyal to the king. The first scene of battle was the city of Gloucester, which Edward, now a young man who could participate in battles, managed to retake from the enemy. When Robert de Ferrers, Earl of Derby, came to the assistance of the rebels, Edward negotiated a truce with the earl, the terms of which he later broke. Edward then captured Northampton from de Montfort's son, also Simon. The baronial and royalist forces finally met at the Battle of Lewes, on 14 May 1264. Edward, commanding the right wing, performed well, and soon defeated the London contingent of de Montfort's forces. Unwisely, however, he followed the scattered enemy in pursuit, and on his return found the rest of the royal army defeated. By the agreement known as the Mise of Lewes, Edward and his cousin Henry of Almain were given up as prisoners to de Montfort.