Pierre de Castelnau was born in the
diocese of Montpellier. He became archdeacon of
Maguelonne, and in 1199 was appointed by
Pope Innocent III as one of the
papal legates for the suppression of the
Cathar heresy in
Languedoc. In 1202, he made a profession as a
Cistercian monk at the
abbey of Fontfroide,
Narbonne, and by 1203 was confirmed as
papal legate and chief
inquisitor, first in
Languedoc, and afterwards at
Viviers and Montpellier. In 1207, Pierre was in the
Rhone valley and in
Provence, where he became involved in the strife between the
count of Baux and
Raymond VI, Count of Toulouse. Castelnau was assassinated on 15 January 1208, possibly by an agent of Raymond, but this was never proven. Nevertheless,
Pope Innocent III held Raymond responsible: Pierre's murder was the immediate cause of Raymond's
excommunication and the start of the
Albigensian Crusade. Pierre was
beatified, through papal order, in 1208 by
Pope Innocent III. The relics of Pierre de Castelnau are interred in the church of the ancient
Abbey of St-Gilles. ==References==