country in April 1263. In March 1264 civil war again broke out, and Peter de Montfort sided with Simon de Montfort against the King. On 2 April 1264 he had a safe conduct to Brackley to meet with Henry III's envoys; however on the following day he and his two sons, Peter and Robert, were at Northampton Castle when the Keeper surrendered it to Simon de Montfort the Younger. On 5 April the castle was retaken by the King, and Peter de Montfort and his sons were taken prisoner and transported to Windsor. They were released after Simon de Montfort's victory at the Battle of Lewes. During the subsequent dominance of Simon de Montfort, Peter de Montfort became one of a nine-member council forced upon the King in June 1264. Thereafter he played a principal role in the government of the county. On 11 September he was appointed one of the envoys who negotiated the reformation of the English government in the presence of Louis IX of France and the Papal Legate. On 16 November he and his heirs were granted the manor of Garthorpe, Leicestershire. On 20 December he was granted custody of Whittington Castle and Hereford Castle. He accompanied Simon de Montfort when the latter journeyed into Wales, and was joint keeper of the royal seal during that time. He was with Simon de Montfort in his final campaign, and was slain with him at the Battle of Evesham on 4 August 1265. His two sons, Peter and Robert, who also took part in the battle, were both wounded and taken prisoner. His place of burial is unknown. He was survived by his wife, Alice. His heirs in the male line died out in 1367. Peter de Montfort's arms were Bendy of eight, Or and azure, although a seal of Peter de Montfort shows only bendy of six. Marriage and issue Montfort married Alice Audley, daughter of Henry Audley, by whom he had two sons, Peter and Robert. His eldest son, Peter de Montfort (d. before 4 March 1287), succeeded him. On 28 June 1267 he was pardoned by Henry III for 'all trespasses at the time of the disturbance in the kingdom', and eventually recovered part of his father's lands. He married Maud de la Mare, daughter of Sir Henry de la Mare (d.1257), of Ashtead, Surrey, by whom he had a son, John, and two daughters,