The chief business of parliament was to complete the settlement of the country.  Simon won a new triumph in making terms with the king’s son.  Edward had witnessed the failure of his mother’s attempts at invasion, the futility of the legatine anathema, and the collapse of the marchers at Worcester.  He saw it was useless to hold out any longer, and unwillingly bought his freedom at the high price that Simon exacted.  He transferred to his uncle the earldom of Chester, including all the lands in Wales that might still be regarded as appertaining to it.  This measure put Simon in that strong position as regards Wales and the west which Edward had enjoyed since the days of his marriage.  It involved a breach in the alliance between Edward and the marchers, and the subjection of the most dangerous district of the kingdom to Simon’s personal authority.  It was safe to set free the king’s son, when his territorial position and his political alliances were thus weakened.

At the moment of his apparent triumph, Montfort’s authority began to decline.  It was something to have the commons on his side:  but the magnates were still the greatest power in England, and in pressing his own policy to the uttermost, Simon had fatally alienated the few great lords who still adhered to him.  There was a fierce quarrel in parliament between Leicester and the shifty Robert Ferrars, Earl of Derby.  For the moment Leicester prevailed, and Derby was stripped of his lands and was thrown into prison.  But his fate was a warning to others, and the settlement between Montfort and Edward aroused the suspicions of the Earl of Gloucester.  Gilbert of Clare was now old enough to think for himself, and his close personal devotion to Montfort could not blind him to the antagonism of interests between himself and his friend.  He was gallant, strenuous, and high-minded, but quarrelsome, proud, and unruly, and his strong character was balanced by very ordinary ability.  His outlook was limited, and his ideals were those of his class; such a man could neither understand nor sympathise with the broader vision and wider designs of Leicester.  Moreover, with all Simon’s greatness, there was in him a fierce masterfulness and an inordinate ambition which made co-operation with him excessively difficult for all such as were not disposed to stand to him in the relation of disciple to master.  And behind the earl were his self-seeking and turbulent sons, set upon building up a family interest that stood directly in the way of the magnates’ claim to control the state.  Thus personal rivalries and political antagonisms combined to lead Earl Gilbert on in the same course that his father, Earl Richard, had traversed.  The closest ally of Leicester became his bitterest rival.  The victorious party split up in 1265, as it had split up in 1263.  And the dissolution of the dominant faction once more gave Edward a better chance of regaining the upper hand than was to be hoped for from foreign mercenaries and from papal support.