The Barons' War (1260-1266) came about due to the misgovernment of Henry III, who continually failed to keep his promises or pay his debts. In 1258 the principal barons of England, led by Simon de Montfort (Earl of Leicester), forced Henry to agree to a plan of government reform (known as the Provisions of Oxford), which restricted royal power by placing the administration of England in the hands of twenty-four barons.
A few years later Henry went back on the agreement and sought to regain his authority, and so the barons took up arms against him.
In the civil war that followed, the northern counties and those along the Welsh border declared for the King, whilst the Midlands and London supported de Montfort.
On 14th May 1264, the armies of both sides met at Lewes in Sussex. The King's supporters formed three bands with Henry in the centre, Richard, Earl of Cornwall, to the left and Prince Edward (only 25 years old) to the right. The barons formed five divisions, with the fourth division made up entirely of Londoners. The King's side was more experienced and stronger but Simon de Montfort had reserves at the ready.
Edward charged at the fourth division and recklessly chased them as they fled, taking himself away from the back-up of the King's other two bands.
Simon de Montfort called in his reserves and attacked the remainder of the King's forces, who were weakened by the Prince's absence. They were crushed and Henry and his chief nobles were captured.
Simon de Montfort now sat as the head of state. He freed Henry but kept Prince Edward hostage at Hereford Castle to maintain control over the King.
De Montfort brought in changes to the make-up of Parliament, which had until now consisted of nobility and clergy. He summoned barons and bishops, two knights from each shire and two townsmen from every city or borough that had supported him.
However, dissent split the barons, and the Earl of Gloucester went over to join the King's side. Prince Edward, whilst exercising on his horse one day on Widemarsh Common in Hereford, escaped to Wigmore Castle and the Mortimer family, who supported the King.
Earl Simon and his son, also named Simon, joined together and marched on Prince Edward, who decided to attack the younger Simon de Montfort. The sudden attack surprised the younger Simon, who managed to escape to Kenilworth Castle in Warwickshire. Edward's men then marched to meet Earl Simon's men to prevent him rejoining his son.
Edward had Earl Simon and his men trapped and outnumbered: Edward's men numbered 20,000 to Simon's 7,000 untrained soldiers. Earl Simon, realising the inevitable outcome, declared "May God have mercy on our souls for our bodies are Edward's."
Simon and his men fought bravely to the end but eventually the Earl was cut down fighting on foot; his body was mutilated and his head mounted on a lance.
In 1266 the Dictum of Kenilworth restored King Henry III to full power, although Prince Edward became the real ruler.
Simon de Montfort the younger survived, and by agreement the rebel barons were granted amnesties and regained their estates by the payment of fines.
[Original author: Miranda Greene, 2003]