Simon de Montfort had returned from France to England in 1263, at the invitation of the barons who were now convinced of the king's hostility to all reform and raised a rebellion with the avowed object of restoring the form of government which the Provisions had ordained.

Henry had quickly given in and allowed Montfort to take control of the council.

His son Edward, however, had begun using patronage and bribes to win over many of the barons.

Their disruption of parliament in October had led to a renewal of hostilities, which saw the royalists able to trap Simon in London.

With few other options available, Montfort had agreed to allow Louis IX of France to arbitrate their dispute.

Montfort had been prevented from presenting his case to Louis directly on account of a broken leg, but little suspected that the king of France, known for his innate sense of justice, would in January 1264 completely annul the Provisions in his Mise of Amiens.

The settlement had not presented a solution to the conflict, but rather a recipe for further problems.

The one-sided decision for the king and against the barons leaves Montfort with little choice but armed rebellion.

Hostilities star already in February, when Montfort's sons, Henry and another Simon, attack the possessions of Roger Mortimer in the Marches.

Henry summons the feudal army, and the royal forces win an important victory at Northampton, where the younger Simon is captured.