Leicester spent the night in prayer, and in early morning knighted Gilbert de Clare, the young Earl of Gloucester, who was at this time enthusiastically attached to him. The battle then began, each army being arrayed in three divisions. Prince Edward and Henry d’Almayne were opposed to their two cousins, Henry and Guy de Montfort, with the bands from London. Mindful of the outrage that his mother had sustained from the citizens, Edward charged them furiously, and pursued them with great slaughter, never drawing rein till he reached Croydon.

But, as they rode back to Lewes, the impetuous young soldiers beheld a sight very different from their triumphant anticipations. The field was scattered with the corpses of the Royalists, and the white-crossed troops of the Barons were closely gathered round the castle and priory of Lewes. In dismay, William and Guy de Lusignan turned their horses, and rode off to embark at Pevensey. Seven hundred men followed them, and Edward and Henry were left with the sole support of Roger Mortimer, a Welsh-border friend of the former, with his followers.

The hot pursuit of the fugitive plunderers had ruined the day. Montfort had concentrated his forces, and had totally routed the two kings; Richard was already his prisoner, and Henry had no chance of holding out in the priory. The princes undauntedly strove to collect their shattered forces, and break through to his rescue, but were forced to desist by a message that, on their first attack, the head of the King of the Romans should be struck off.

To save his life, the two cousins therefore agreed to a treaty called the Mise of Lewes, May 15th, 1264, by which they gave themselves up to the Barons as hostages for their fathers, stipulating that the matter at issue should be decided by deputies from the King of France, and that the prisoners on either side should be set free.

Now began the great trial of Simon de Montfort—that of power and prosperity—and he failed under it. Whatever might have been his first intentions in taking up arms, he now proved himself unwilling to lay aside the authority placed in his hands, even though he violated his oaths in maintaining it, and incurred the sentence of excommunication which the Pope launched against him. But when the most saintly English bishops of their own time had died under it, it lost its power on the conscience.

No measures were taken for the French arbitration, nor were the prisoners set free. The King of the Romans was confined at Kenilworth, and the two young princes at Dover, the custody of which castle was committed to one of their cousins, the Montforts, who allowed them no amusement but the companionship of Thomas de Clare, the young brother of the Earl of Gloucester. King Henry was indeed nominally at liberty, but watched perpetually by Leicester’s guards, and not allowed to take a step or to write a letter without his superintendence; and when the Mayor of London swore fealty to him, it was with the words, “As long as he was good to them.” Edward was made, on promise of liberation, to swear to terms far harder than even the Acts of Oxford, and when the bitter oath had been taken, he was pronounced at full liberty, and then carried off, under as close a guard as ever, to Wallingford Castle.

Queen Eleanor was acting with great spirit abroad, gathering money and collecting troops in hopes of better times, and seven knights still held out Bristol for the King. They made a sudden expedition to Wallingford, in hopes of rescuing the Prince; but the garrison were on the alert, and called out to them that, if they wanted the prince, they might have him, but only tied hand and foot, and shot from a mangonel; and Edward himself, appearing on the walls, declared that, if they wished to save his life, they must retreat.

This violent threat went beyond the instructions of Leicester, who removed his nephew from the keeping of this garrison, and placed him at Kenilworth.

But Simon was made to feel that he had little control over his followers, and especially over his wild sons, who had learnt no respect to authority at all, and outran in their violence even the doings of the Lusignan family. Henry de Montfort seized all the wool in England, which was sold for his profit, while Simon and Guy fitted out a fleet and plundered the vessels in the Channel, without distinction of English or foreigners, and thus turned aside the popularity which Leicester had hitherto enjoyed in London. The Barons, too, already discontented at having only changed their masters, so as to have the mighty Montfort over them instead of the weak Plantagenet, could not bear with the additional lawlessness of sons who made themselves vile without restraint. A violent quarrel arose between these youths and Earl Gilbert de Clare, who challenged them to a joust at Dunstable; but their father, dreading fatal consequences, forbade it, and Gloucester retired to his estates in high displeasure.

Here he was joined by his brother Thomas, who came full of descriptions of the princely courtesy and sweetness of manner of the royal Edward, which contrasted so strongly with the presumption of his upstart cousins that the young Earl was brought over to concert measures with the Prince’s friend, Roger Mortimer.