Author of the Historia Albigensis, a history of the anti-Cathar preaching mission and the Albigensian Crusade (1209-1229) in southern France.
Probably born around 1190, Peter became a monk at the Cistercian monastery of Vaux-de-Cernay near Paris. He participated in the Fourth Crusade (1202-1204) as well as the Albigensian Crusade along with his uncle Guy, abbot of Vaux-de-Cernay.
Peter’s Historia Albigensis, written in Latin in several redactions from around 1212 to 1218, is one of the central sources for the Cistercian preaching mission against heresy and the early phases of the Albigensian Crusade. It was begun in the winter of 1212-1213 in response to Pope Innocent III’s attempts to wind down the antiheretical crusade in preparation for a new crusade to the Holy Land, and sought to persuade Innocent and its other readers that the resistance to conversion of local heretics and the recalcitrant obstructionism of Count Raymond VI of Toulouse and other native nobles who shielded the heretics justified a sustained military campaign against heresy in Languedoc. Present in that region from roughly 1212 to 1218, Peter also drew on eyewitness accounts from his uncle and other Cistercian abbots, preachers, legates, and prelates to depict the “failure” of the antiheretical preaching efforts, which necessitated the crusade led by Simon of Montfort, whom Peter portrays as the archetype of the impeccably orthodox rulers needed to extirpate heresy in Languedoc. His history is preserved in several monasteries associated with those preaching the crusade, suggesting that it may also have served as a source for antiheretical and crusading propaganda.