The war also involved a series of massacres of Jews by de Montfort's supporters, including his sons Henry and Simon, in attacks aimed at seizing and destroying evidence of baronial debts.

To bolster the initial success of his baronial regime, de Montfort sought to broaden the social foundations of parliament by extending the franchise to the commons for the first time.

Their relationship reached a crisis in the 1250s, when de Montfort was put on trial for actions he took as lieutenant of Gascony, the last remaining Plantagenet lands across the English Channel.

Measures against the Jews and controls over debts and usury dominated debates about royal power and finances among the classes that were beginning to be involved in Parliament, and supported de Montfort in the war.

Under the Treaty of Kingston, an arbitration system was agreed upon to resolve outstanding disputes between Henry and the barons, with de Clare as the initial arbiter and the option of appealing his verdicts to Louis IX.

The King's position was further weakened by the death of Richard de Clare and the succession of his son Gilbert, who sided with the opposition, and by the reversal of the papal annulment of his oath to uphold the Provisions.

With violent disorder spreading and the prospect of all-out war, Henry appealed to Louis for arbitration, and, after initial resistance, de Montfort consented.

Some of the barons who had opposed Henry acquiesced in the verdict, but a more radical faction led by de Montfort prepared to resist any reassertion of royal power, and they and the king gathered their forces for war.

[3] A series of attacks on Jewish communities followed, organised by key allies of de Montfort, hoping to gain by destroying the records of their debts to moneylenders.

[2] In April, the elder Simon de Montfort, in control of London, assembled his forces at St Albans and marched to relieve Northampton, which was under siege by the royalists, but he was too late to prevent the town's capture by betrayal.

While Henry was reduced to a figurehead king, de Montfort broadened parliamentary representation to include groups beyond the nobility, members from each county of England and many important towns.

Eventually, Simon the Younger reached the baronial stronghold of Kenilworth, but Edward managed to inflict great losses on his forces, many of whom were quartered outside the castle walls.

[8] The elder Simon had taken advantage of Edward's move to Kenilworth to cross the Severn at Kempsey and was on his way to join his son when he was intercepted and decisively defeated by the royalists at the Battle of Evesham on 4 August.

King Henry was persuaded to seek a compromise settlement, and a commission of bishops and barons drafted a proclamation, known as the Dictum of Kenilworth, issued on 31 October.