As usual, the initial fighting broke out in the west. Henry de Montfort scored an early triumph by bottling up Edward in Gloucester, but then unwisely accepted his cousin’s call for a truce. He had no sooner withdrawn his forces when Edward sacked the town and slipped away, causing Simon to bitterly reproach his son. The king meanwhile began gathering a large army at Oxford, where one of his first acts was to expel the student population. His intention, he explained, was to protect them from the savagery of his Scottish allies, but in fact he was clearly miffed by their true sympathies. Henry’s growing strength allowed him to brush aside a last-ditch offer by his opponents to respect Louis’ ruling on every point except the alien officials. The advantage was all his after he seized the Montfortian stronghold of Northampton, which was betrayed by local clergymen. The loss was devastating. Among the eighty barons and knights made prisoner were the younger Simon and many leading members of the movement. Montfort refused to despair. “War is such that the advantage first goes to these, then to those,” he declared and followed up by predicting that the enemy would be consumed by fear and confusion before May was out. London, however, was gripped by panic as word spread it was about to be betrayed like Northampton, resulting in the plunder and massacre of the Jews. As royalist forces burned and butchered their way through local hamlets, Simon attempted to draw them south by laying siege to their garrison in Rochester, whose inhabitants were subjected to a similar bloodletting. With barely London left to the reformist party, Simon gambled everything on seeking out and giving battle to the king. The two sides squared off in Sussex, with the royalists encamped in and around the village of Lewes and the Montfortians eight miles away in Fletching. Simon sent his bishop friends to Henry to reiterate his offer of peace if the king would observe only the provision prohibiting alien officials, sweetening it now to include 30,000 marks in compensation. Henry was inclined to accept, but Richard, aggrieved that his property had been ransacked, was against it, as was Edward. The one-time idealist and reformer declared that peace was only possible if his uncle and the others came to them with halters around their necks.
A truce was to be observed during the course of arbitration. Henry being Henry, he ordered Roger Mortimer, an exceedingly violent man even for a marcher baron, to attack Simon’s manors in the hope of preventing his adversary from attending the proceedings in person. He knew the reformist side hinged on Montfort’s powers of persuasion and his friendship with Louis. In the end, all it took was a hole in the ground. While heading south for Dover, Montfort suffered a broken leg when his horse stumbled and fell. Forced to stay behind, he was no doubt confident the king of France would still rule close to his original affirmation of the Provisions. Louis, however, stunned everyone by completely nullifying them in his Mise of Amiens issued on 23 January 1264. Acting “unmindful of his own honour,” in the words of one chronicler, he declared that Henry had the right to appoint any official he saw fit, whether native-born or not. He tried to evade responsibility by insisting that the pope had nullified the Provisions first, then hedged by assuring the people of England that Magna Carta was in no way affected by his ruling. Sworn to abide by the award, Simon and his associates justified their continuing resistance by arguing that the Provisions were founded on the principles of Magna Carta. Louis’ betrayal, which was variously attributed to bribes, nagging or some concerted action with the papacy, rankled deeply. “Though all may forswear me, I will stand firm with my sons in the just cause to which my faith is pledged,” Simon proclaimed, adding gloomily that of all the lands he had been to, never had he met with more treachery than in England. But he did get some help when Gilbert de Clare finally decided to join forces with him and London remained firmly committed to the reformist cause. Civil war was now inevitable.
Father and son were soon reconciled, mostly because Henry, whatever his other faults, was a devoted family man. Relations between the Lord Edward, as he was called at the time, and his uncle remained amiable, even after the king vengefully ordered Montfort to stand trial for obstructing the peace treaty and defying his orders. Clare, worried that his part in defaming Edward would become known, managed to get the trial delayed. Then an uprising by the Welsh forced Henry to turn to Simon for his military skills and the trial soon was shelved for good. The parliament of October 1260 marked Montfort’s return to government as an ally of Edward, who knighted his sons Henry and Simon. The council even allowed him to appoint Richard’s son Henry of Almain to represent him in his official capacity as steward of England, another move which offended the king. More notably, he reached a compromise with Clare to have the top crown officials replaced with his supporters and Edward’s in return for agreeing to modify local reforms to better suit the interests of magnates like Clare. Even so, one of the first acts of the new justiciar, Montfortian Hugh Despenser, was to hear cases against magnate Peter of Savoy, one of the Seven but now completely in the king’s camp. Henry fumed about these appointments, but his circle of advisers – the queen and her Savoyard relatives – urged him to bide his time. They had a plan in place that would quash the Provisions and make Henry the master of his realm again. The first part called for letting Edward go abroad to joust and carouse with a large retinue that included his Montfort cousins. The removal of these young idealists would give Henry a free hand to purge his council of Clare and Simon, who in any case had gone to France with Eleanor for the probate action she launched against her Lusignan half-brothers. While there, Simon asked Louis to arbitrate between him and Henry, and both kings agreed. As desperate as Henry was to mollify his sister and brother-in-law, his more immediate concern was carrying out the second part of the plan. As stipulated by the Provisions, he summoned parliament to meet in February 1261, only the venue was the Tower of London. Clare, Simon and the other magnates arrived to find armed militia waiting in the wings. “Now, gentlemen,” said the king.
Impressed by this practical approach, the pope gave his blessing. The marriage was further helped by the arrival of their firstborn eleven months after the secret wedding, which should have quashed certain nasty rumors circulating about. They named the boy after Henry, and when the king’s own firstborn finally arrived the following year, he was named Edward in honor of Edward the Confessor, Henry’s true inspiration for building Westminster Abbey. Young Henry de Montfort would become Edward’s first boyhood companion, later his jailer after the baronial forces captured his cousin during the civil war. When Edward escaped and rallied the royalists to defeat the opposition once and for all, young Henry fell fighting alongside his father. It is reported that Edward wept upon seeing his body lying on the field of slaughter, but then he had made sure this particular battle, at Evesham in 1265, ended in slaughter.