Pierre de Castelnau French ecclesiastic, was born in the diocese of Montpellier.

In 1199 he was archdeacon of Maguelonne, and was appointed by Pope Innocent III

Pope Innocent III

Pope Innocent III was Pope from 8 January 1198 until his death. His birth name was Lotario dei Conti di Segni, sometimes anglicised to Lothar of Segni....

 as one of the legate

Papal legate

A papal legate – from the Latin, authentic Roman title Legatus – is a personal representative of the pope to foreign nations, or to some part of the Catholic Church. He is empowered on matters of Catholic Faith and for the settlement of ecclesiastical matters....

s for the suppression of the Cathar

Cathar

Catharism was a name given to a Christian religious sect with dualistic and gnostic elements that appeared in the Languedoc region of France and other parts of Europe in the 11th century and flourished in the 12th and 13th centuries...

 heresy in Languedoc

Languedoc

Languedoc is a former province of France, now continued in the modern-day régions of Languedoc-Roussillon and Midi-Pyrénées in the south of France, and whose capital city was Toulouse, now in Midi-Pyrénées. It had an area of approximately 42,700 km² .-Geographical Extent:The traditional...

.

In 1202, when a monk in the Cistercian abbey of Fontfroide, Narbonne

Narbonne

Narbonne is a commune in southern France in the Languedoc-Roussillon region. It lies from Paris in the Aude department, of which it is a sub-prefecture. Once a prosperous port, it is now located about from the shores of the Mediterranean Sea...

, he was designated to similar work, first in Toulouse

Toulouse

Toulouse is a city in the Haute-Garonne department in southwestern FranceIt lies on the banks of the River Garonne, 590 km away from Paris and half-way between the Atlantic Ocean and the Mediterranean Sea...

, and afterwards at Viviers

Viviers

Viviers is the name or part of the name of several communes in France:* Viviers, Ardèche, in the Ardèche département, capital of the Vivarais and episcopal see* Viviers, Moselle, in the Moselle département...

 and Montpellier.

In 1207 he was in the Rhone valley and in Provence, where he became involved in the strife between the count of Baux and Raymond, count of Toulouse

Raymond VI of Toulouse

Raymond VI was count of Toulouse and marquis of Provence from 1194 to 1222. He was also count of Melgueil from 1173 to 1190.-Early life:...

. Castelnau was assassinated on 15 January 1208, quite possibly by an agent of Raymond. His murder was the immediate cause of Raymond'e excommunication

Excommunication

Excommunication is a religious censure used to deprive, suspend or limit membership in a religious community. The word means putting [someone] out of communion. In some religions, excommunication includes spiritual condemnation of the member or group...

 and the start of the Albigensian Crusade

Albigensian Crusade

The Albigensian Crusade or Cathar Crusade was a 20-year military campaign initiated by the Catholic Church to eliminate Catharism in Languedoc...

.

He was beatified in the year of his death by Pope Innocent III, who held Raymond responsible.

His death is also portrayed in Elizabeth Chadwick

Elizabeth Chadwick

Elizabeth Chadwick is an author of historical fictions. She is a member of Regia Anglorum, a Medieval reenactment organisation.-Biography:Elizabeth Chadwick was born in Bury, Lancashire. She moved with her family to Scotland when she was four years old and spent her childhood in the village of...

's work of historical fiction, "Daughters of the Grail".

The relics of Pierre de Castelnau are interred in the church of the ancient Abbey of St-Gilles.