Pope (1048–54). An able church reformer, he enlisted like‐minded churchmen to assist him including Hildebrand (later Pope Gregory VII). His chief concerns were simony and clerical celibacy; at the Easter synod of 1049 celibacy was enforced on all clergy. Attempting to establish papal control in southern Italy, Leo’s forces were defeated by the Normans and he was made prisoner. His interference in south Italy in areas claimed by the Byzantine empire led to the East–West Schism of 1054 when the Patriarch of Constantinople was excommunicated. He died soon after being released from prison and, for his work in restoring the prestige of the papacy, was declared a saint.