Peter of Castelnau

Peter of Castelnau was a French ecclesiastic who was appointed by Pope Innocent III as one of the papal legates for the suppression of the Cathar heresy in Languedoc. He was born in the diocese of Montpellier and became an archdeacon of Maguelonne. In 1202, he joined the Cistercian order at Fontfroide Abbey. He gained the recantation of Raymond VI of Toulouse, who was allowing the heresy to spread throughout his domain. However, Raymond soon relapsed and Peter excommunicated him and placed his lands under interdict. Peter also faced opposition from other nobles and clergy who supported the Cathars. On January 14, 1208, he was assassinated by a knight in Raymond's service near Saint-Gilles. His death provoked Pope Innocent III to launch the Albigensian Crusade, a holy war against the Cathars and their allies. Peter was venerated as a martyr in the dioceses of southern France and his relics were enshrined in the church of Saint-Gilles.