Simon de Montfort beat Henry III on the downs above Lewes on 14 May 1264, capturing the king, his brother and his son, and took control of the English government for the next fifteen months.
On 14 May 1264 Simon de Montfort, Earl of Leicester, came down off the Sussex downs and destroyed the army of Henry III of England outside Lewes. It was the first pitched battle of the Second Barons’ War, and it ended with the king, his brother Richard of Cornwall and his eldest son the Lord Edward all in baronial hands. For the next fifteen months England was governed in Henry’s name by a council Montfort controlled, and it was that council which summoned the parliament of January 1265.
The battle was decided by ground and by one man’s impatience. Montfort seized the crest of Offham Hill before dawn and held a division back as a reserve. Edward, commanding the royal right, broke the London infantry in front of him and then pursued them some four miles, taking the best of the royal cavalry with him; by the time he returned, his father’s divisions had been pushed downhill into the streets of the town. The agreement reached that night, the Mise of Lewes, gave Montfort the government of England and settled almost nothing else, and the questions it left open killed him at the Battle of Evesham fifteen months later.
The quarrel began in 1258, when a coalition of magnates forced the Provisions of Oxford on Henry III: a council of fifteen chosen with the barons, parliaments three times a year, and reforming justices sent into the shires. Henry never accepted the arrangement as permanent. In 1261 he obtained papal absolution from his oath to keep it and resumed personal rule, and the reforming party splintered over whether the Provisions bound the king alone or the great lords as well.
Both sides then made the mistake of asking someone else to decide. They submitted the dispute to Louis IX of France, who gave judgment at Amiens on 23 January 1264 and annulled the Provisions outright, restoring Henry’s full authority. The Mise of Amiens left Montfort with no lawful route to the reform he had staked everything on, and fighting began within weeks in the Welsh Marches.
The opening campaign went badly for the barons. Royal forces stormed Northampton in April 1264 and took Montfort’s son Simon the Younger prisoner there, then moved on Rochester and into the south-east. Montfort marched out of London with an army thick with citizen levies, and on 13 May the two hosts lay within a few miles of each other at Lewes: the king quartered at the Cluniac priory of St Pancras south of the town, Edward with the cavalry in the castle, and the Montfortians camped in woodland to the north between Offham and Hamsey. Montfort sent terms; Henry and Edward returned formal defiance.
Henry III had the larger and far better mounted army. The Battlefields Trust puts it at perhaps 1,500 mounted knights with two to three thousand foot, which is the only responsible estimate available; the round figures of ten thousand against five thousand that circulate in popular accounts preserve a rough two-to-one ratio rather than any count, because no muster roll for either side survives. What the chroniclers agree on is the shape of the mismatch: the king had the knights, and a large part of Montfort’s infantry were Londoners with little training and worse equipment.
Montfort drew up in four divisions. His sons Henry and Guy held the right with John de Burgh and Humphrey de Bohun; the Londoners under Nicholas de Segrave and Henry de Hastings took the left; Gilbert de Clare, Earl of Gloucester, commanded the centre with John FitzJohn and William de Munchensy; and Montfort himself kept the fourth division back as a reserve, which was the decision that won the battle. The royal army formed in three: Edward on the right with William de Valence and John de Warenne, Richard of Cornwall and his son Henry of Almain in the centre, and the king on the left.
The ground did the rest. In the early hours Montfort moved his army up to the crest west of the town, to a place the sources call Boxholte, and had his men marked with white crosses. Holding the hill meant the royalists had to come up at him out of Lewes, and it put the town, the castle and the priory at their backs — comfortable quarters that turned into a trap once the line broke.
The fighting opened at first light with a baronial attack on royalist foragers who had come out of the town, which brought both armies out in earnest before the king’s divisions were properly formed. On the royal right Edward charged the Londoners facing him and broke them at once. He had a private reason to hate them: the year before, a London crowd had pelted his mother, Eleanor of Provence, from London Bridge as her barge tried to leave the city. He drove the fugitives north and west for about four miles, killing as he went.
That pursuit lost the battle. With Edward and the heavy cavalry gone, Montfort committed his reserve against a royal army now fighting uphill with one wing missing. Richard of Cornwall’s division gave way first, and the king’s followed; the royalists were pressed back down the slope and into the streets. Richard, unable to reach the priory, took refuge in a windmill and was captured there, jeered by the barons’ men as a wicked miller who should come down out of his mill.
Henry fought his way back to the priory of St Pancras with what was left of his centre and left. Edward returned to find the field gone, cut his way through to his father, and briefly argued for fighting on from the priory and the castle; the town was burning in places and the baronial army held everything outside. Negotiations began that evening. Casualty figures are not recoverable — the chronicle tradition gives some 2,700 dead on the royal side, a number no independent source confirms — but the dead were heaviest among the Londoners Edward had ridden down and the royalist foot caught in the streets.
The terms agreed on 14 May are known as the Mise of Lewes, and the document itself does not survive, which is why historians still argue about what was in it. Noel Denholm-Young reconstructed it in 1933 as an agreement that handed over the Lord Edward and Henry of Almain as hostages, freed the baronial prisoners taken at Northampton, and referred a permanent settlement to a committee of French clergy and nobles. John Maddicott argued in 1983 that the Provisions of Oxford must have been named in it, since they were the whole point of the war; David Carpenter suggested in 1985 that it was agreed during the fighting rather than after it, which would mean Montfort conceded things he had no intention of honouring once he had won.
What is not in doubt is the effect. Henry kept his crown, his title and his person, and lost the government: a council of nine now ruled, chosen under Montfort’s influence, and the king’s heir was a hostage for his father’s good behaviour. The promised French arbitration never produced a settlement, partly because the queen, Eleanor of Provence, was in France raising ships and mercenaries to invade, and partly because no arbitrator could give both sides what they had fought for. The Mise was a pause, not a peace.
One clause had consequences beyond the war. Debts owed to England’s Jewish community were cancelled and the records of them destroyed, a war aim of the indebted knights who made up much of Montfort’s support, and one pursued in the months before the battle through attacks on the Jewish communities of London, Canterbury and elsewhere. The reform movement that produced the first English parliament with elected townsmen in it also produced that.
Montfort’s fifteen months of power are the reason Lewes is remembered. In January 1265 his government summoned a parliament that called two knights from each shire and, for the first time, two burgesses from each borough — not because Montfort was a democrat, but because he needed the towns and the lesser gentry behind a regime the greater barons were deserting. The precedent outlasted the man.
It could not hold. Gilbert de Clare, who had commanded the baronial centre at Lewes, fell out with Montfort over the spoils and the Montfort family’s grip on castles and offices, and went over to the royalists in the spring of 1265. On 28 May the Lord Edward escaped from custody at Hereford, and the war restarted with the hostage of Lewes now leading an army. Montfort was killed at the Battle of Evesham on 4 August 1265.
Lewes also fixed a tactical lesson that Edward applied for the rest of his life. He had won his own fight and lost the battle by chasing it; at Evesham he took the high ground, blocked the escape route first, and did not move until the trap was shut. The Song of Lewes, a Latin poem written by a partisan of the barons soon after the victory, argued that a king who will not rule by counsel may be constrained by his subjects — the clearest statement of what the war was actually about, and a line from it is cast into the memorial that now stands on the priory ground where Henry surrendered.