Pinchon, Guillaume a French prelate of note, was born in the parish of St. Alban. near St. Brieuc, in 1184. He took holy orders in 1207, and was made canon of St. Brieuc; then of St. Gatien de Tours; and, in 1220, bishop of St. Brieuc. Pierre Mauclerc, duke of Brittany, made an attempt at that time to encroach upon the secular rights which the bishops of the province enjoyed in their bishoprics, and he issued ordinances by which the clergy were deprived of their most important privileges. Guillaume, acting in accord with the other prelates of the duchy, excommunicated Mauclerc, who, having assembled a number of his barons at Redon, decided that the bishops should be banished. Guillaume retired to Poitiers, where he acted, for some time, as coadjutor of Philippe, bishop of that city, during a severe illness of this prelate (1229). His rights having been recognized by Pierre Mauclerc, he returned to his see in 1231, and kept busy during the rest of his life in reforming the abuses which had spread among the clergy during his absence, and continuing the reconstruction of his cathedral. Guillaume Pinchon died at St. Brieuc July 29, 1234. He was canonized by Innocent III in 1247. His complete relics were discovered in 1847 in the cathedral. The Church of St. Brieuc and of Treguier devotes to his memory the 29th of July. — Hoefer, Nouv. Biog. Géneralé, 40, 248.