Montfort, Simon de (c. 1208–1265)

English politician and soldier. From 1258 he led the baronial opposition to Henry III's misrule during the second Barons' War, and in 1264 defeated and captured the king at Lewes, Sussex. In 1265, as head of government, he summoned the first parliament in which the towns were represented; he was killed at the Battle of Evesham during the last of the Barons' Wars.

Initially one of Henry III's favourites, he married the king's sister Eleanor in 1238. He later disagreed with the king's administrative policies, and in 1258 Montfort and his baronial supporters forced Henry to accept the Provisions of Oxford, by which the king's powers were in effect transferred to a committee of barons. These provisions were anulled by the Dictum of Kenilworth in 1266, after the final defeat of Montfort's followers, and their lands and titles were confiscated.

Born in Normandy, the son of Simon de Montfort (c. 1160–1218) who led a crusade against the Albigenses, he arrived in England in 1230, and was granted the earldom of Leicester.