Pembroke, Aymer de Valence, earl of (pĕmˈbrŏk) [key], d. 1324, English nobleman; nephew of Aymer of Valence, bishop of Winchester. He succeeded his father, William, half-brother of Henry III, as earl of Pembroke in 1296. Sent by Edward I to suppress the Scottish uprising, he defeated Robert I at Methven (1306) but was himself defeated at Loudon Hill (1307). Under Edward II he was one of the lord's ordainers, appointed to limit the king's power. Disgusted by the murder (1312) of Piers Gaveston, the royal favorite, Pembroke switched his support to the king. He fought for Edward at Bannockburn (1314). By 1318 he had organized a moderate royalist group of barons, which mediated successfully between the king and the rebellious barons until displaced (1322) by Hugh le Despenser, the elder, and his son. Pembroke died suddenly on a diplomatic mission to France.
See study by J. R. S. Phillips (1972).