At the Siege of Toulouse, Simon de Montford's Father is killed. Him and his Brother agree that he should be Earl of Leicester .
Simon and Henry III fall out over the war in France. The Barons impose the Provisions of Oxford on the King, reducing his powers.
The Great Parliament
de Montford and some of the Barons feel that the Provisions of Oxford are progress, but want the king to concede more of his power. They create the provisions of Westminster.
de Montford goes into exile, but returns 4 years later, and asks the King of France to decide who he thinks is right in the matter. He says that Henry was correct. The 2nd Barons War begins.
The Barons win a crushing victory and Henry and his son, Edward, are captured by de Montford. He summons all the Lords and some representatives from counties and towns to the Great Parliament.
However, support for de Montford is failing. Edward escapes prison and raises an army. There was a skirmish at Kennilworth Castle before the Battle of Evesham where de Montford's forces where wiped out.