WILLIAM OF VALENCE (d. 1296), brother of Henry III. of England, was a son of John's widow, Isabelle of Angouleme, by her second marriage. William came to England with his brothers in 1247, and at once became a court favourite. He mar ried Joan de Munchensi, the heiress to the Pembroke estates, whence he is sometimes styled earl of Pembroke. In 1258 he was attacked by the baronial opposition and forced to leave England. He returned in 1261, after Henry III. had repudiated the Pro visions of Oxford, and fought on the royal side at Lewes (1264). Escaping from the pursuit of the victorious Montfortians, he later appeared at the head of a small army in Pembrokeshire.
This gave the signal for the outbreak of a new civil war which ended with the defeat of Montfort at Evesham (1265). Valence accompanied Prince Edward to the Holy Land and, in later years, became a trusted agent of the crown, especially in the Welsh wars. The position of his estates made him the natural leader of all ex peditions undertaken against Llewelyn from South Wales. He was also employed in Aquitaine. He died at Bayonne in 1296.
See R. Pauli's Geschichte von England, vol. iii. (Hamburg, 1853) W. H. Blaauw, Barons' War (1871).