Mise of Lewes The Mise of Lewes was a settlement made on 14 May 1264 between King Henry III of England and his rebellious barons , led by Simon de Montfort . The settlement was made on the day of the Battle of Lewes , one of the two major battles of the Second Barons ' War . The conflict between king and magnates was caused by dissatisfaction with the influence of foreigners at court , and Henry ' s high level and new methods of taxation . In 1258 Henry was forced to accept the Provisions of Oxford , which essentially left royal government in the hands of a council of magnates , but this document went through a long series of revocations and reinstatements . In 1263 , as the country was on the brink of civil war , the two parties agreed to submit the matter to arbitration by the French king Louis IX . Louis was a firm believer in the royal prerogative , and decided clearly in favour of Henry . The outcome was unacceptable for the rebellious barons , and war between the two parties broke out almost immediately . The Mise of Lewes was signed on the day of Montfort ' s victory at the Battle of Lewes , though it is not known whether it happened during or after the battle . Neither are the terms of the document known , though it seems clear that they involved conditions for further negotiations . These efforts at a permanent settlement fell through , however , and the support for Montfort ' s government gradually eroded . Henry ' s oldest son , Edward – the later King Edward I started a military campaign that ended in the Battle of Evesham in August 1265 , where Earl Simon was defeated and killed . Parts of the baronial resistance still held out , but by the end of 1266 the final besieged garrison at Kenilworth Castle surrendered . The rebels were given pardons according to terms set out in the Dictum of Kenilworth . Background . By 1264 , the reign of Henry III was deeply troubled by disputes between the king and his nobility . The conflict was caused by several factors : the influence of foreigners at court , a wasteful war over the crown of Sicily , and a personal dispute between King Henry and Simon de Montfort , Earl of Leicester . In 1258 , Henry was forced to accept the so - called Provisions of Oxford , whereby he effectively surrendered control of royal government to a council of magnates . In 1259 the baronial program of reform was further elaborated upon in the Provisions of Westminster . The provisions remained in effect for three years ; it was not until 1261 that Henry was able to move against the opposition . Receiving the papal annulment of the provisions his emissaries had campaigned for , he re - assumed control of government . Over the next two years , however , discontent re - emerged over Henry ' s style of government . He failed to reconcile with Montfort , and alienated Gloucester ' s son and heir Gilbert . In April 1263 Simon de Montfort returned to England after a long stay in France , and reignited the reform movement . On 16 July Henry was surrounded by rebel forces in the Tower of London , and once more forced to accept the conditions of the provisions . Prince Edwardthe later King Edward I – now took control of the situation . In October Edward took Windsor Castle , and the baronial alliance started to break up . Cornered , Montfort had to accept a truce and agree to submit the issue to arbitration by the French king Louis IX . By the Mise of Amiens , Louis decided entirely in favour of Henry , and repudiated the provisions . The settlement did not present a solution to the conflict , but rather a recipe for further problems . The one - sided decision for the king and against the barons left Montfort with little choice but armed rebellion . Hostilities started already in February , when Montfort ' s sons , Henry and another Simon , attacked the possessions of Roger Mortimer in the Marches . Henry summoned the feudal army , and the royal forces won an important victory at Northampton , where the younger Simon was captured . Montfort was still in control of London , as Henry regained control over Kent and Sussex . Montfort marched out of London to negotiate , but the termsinvolving maintaining the provisionswere rejected by the king . The only option remaining was to fight , and the two forces met at Lewes on 14 May 1264 . In spite of inferior numbers , the baronial forces led by Simon de Montfort won the battle . Edward , commanding the right wing , quickly defeated the London forces . When he set out in pursuit of the fleeing soldiers , however , he left the rest of the royal army exposed . The baronial forces took advantage of the situation , and soon won the day . Settlement . Since no documents exist to confirm the content of the Mise of Lewes , there has been much debate among historians over its content , and the circumstances under which it was written . Noël Denholm – Young , in an article published in 1933 , made a conjecture on what the main points of the agreement were . The first point , according to Denholm - Young , was that Prince Edward and his cousin , Henry of Almain , should be given over to the barons as hostages . Secondly , those of the baronial party who had been taken hostage at Northampton were to be released . Thirdly , those who had taken hostages from the royalist party at the Battle of Lewes were to receive ransom . Finally , it was agreed that a committee of French clergy and nobles should arbitrate over a permanent settlement . This interpretation has been largely followed by later historians . One contentious point in Denholm - Young ' s article was his assertion that there was no mention of the Provisions of Oxford in the Mise of Lewes . This was an idea that John Maddicott strongly contested in an 1983 article . According to Maddicott , the provisions had been at the centre of Montfort ' s opposition over the last six years , and it was unlikely that he would give them up so easily . Nevertheless , Montfort showed willingness to negotiate the terms of the provisions . As such , the Mise of Lewes was a moderate document ; Montfort wanted to avoid a repetition of the situation after the Mise of Amiens . Rather it was external circumstances outside of Montfort ' s control that led to the eventual failure of the negotiations between the royalists and the barons . This interpretation was challenged by David Carpenter two years later , in 1985 . Montfort had no intention to compromise with the royalists at all , according to Carpenter . In Carpenter ' s version of events , the Mise of Lewes was written while the battle was still ongoing , not after the battle was over , as previously assumed . This put Montfort in a situation where concessions were necessary , in order to bring hostilities to a halt as soon as possible . Once the battle was over and government in Montfort ' s hands , he had no longer any interest in reaching a compromise with the royalists , and that was why hostilities continued . This dating of the document , however , has later been disputed by D . W . Burton , who maintains that the document was in fact signed after the battle was concluded . Aftermath . The government led by Montfort soon ran into problems ; he faced poor finances , general disorder , and the threat of invasion from exiled royalists in France . It was decidedsince the French arbitration committee had come to nothingto set up a provisional administration , consisting of Montfort , the young Earl of Gloucester , and the Bishop of Chichester . These three were to elect a council of nine , to govern until a permanent settlement could be reached . By the Peace of Canterbury in August , Henry and Edward were forced to accept even stricter terms than those of the Mise of Lewes . According to this new agreement , the current form of government was to remain in force throughout the reign of King Henry , and into that of Edward . To keep the borders safe , Montfort had been forced to release Roger Mortimer and other royalist Marcher lords after the Battle of Lewes . In December , Montfort forced Mortimer , Roger de Clifford and Roger de Leybourne to promise to leave the country for Ireland . Then , in January , he summoned a parliament with representatives from the shires and boroughs ; an innovation in English government . Here Montfort secured the support of the community of the realm for his continued reign . Montfort ' s success was illusory , however . The terms of the Peace of Canterbury were rejected by a papal legate in negotiations at Boulogne . Meanwhile , the Marcher lords did not leave the country , and remained a thorn in the side of the regime . The triumvirate at the head of government broke up when the Earl of Gloucester defected to the royalist side . In May , Edward was able to escape captivity , with Gloucester ' s help . Edward started on a campaign of re - conquest , while Montfort was forced to suppress a rebellion in the Marches . He succeeded only by making large concessions to Llewelyn , and then moved east to join forces with his son Simon . Edward , however , routed the younger Simon at Kenilworth Castle . On 4 August 1265 Montfort found himself trapped at Evesham , forced to give battle with a much smaller army than the royals . The battle soon turned into a massacre ; Montfort himself was killed and mutilated on the field . Even with Montfort dead resistance remained , particularly at the virtually impregnable Kenilworth Castle . In October 1266 the Dictum of Kenilworth set down terms by which the rebels could obtain pardons , and by the end of the year the garrison surrendered .