A Papal Crusade Killed an Estimated 200,000 Cathars in Southern France

The Cathars were a dualist Christian movement that spread through southern France, northern Italy, and parts of the Rhineland between roughly 1100 and 1300. Their theology held that the visible material world had been created not by the good God of the Gospels but by a malign creator, Rex Mundi, the King of the World, and that salvation lay in renouncing material existence. They rejected the Catholic clerical hierarchy, the sacraments, and most of the institutional church, and conducted their own initiation, the consolamentum, by laying-on of hands rather than water baptism. The Languedoc region of southern France was substantially tolerant of them through the 12th century — Occitan-speaking, urbanized, governed by counts who didn't always answer to Paris.

In January 1208 a Cistercian papal legate, Pierre de Castelnau, was murdered in the Rhône Valley in circumstances that pointed to Count Raymond VI of Toulouse, a Cathar sympathizer. Pope Innocent III responded by calling a crusade. Twenty thousand or so Catholic knights and footmen marched south from Lyon under the command of the abbot Arnaud Amalric. The first major target was Béziers, a Languedoc city of mixed Catholic and Cathar population, in July 1209. The chronicle attributed to Caesarius of Heisterbach reports that when soldiers asked the legate how to distinguish the faithful from the heretics, Arnaud Amalric replied, "Caedite eos. Novit enim Dominus qui sunt eius" — "Kill them all. The Lord will know his own." Whether the words were actually said is debated; the conduct was not. Béziers was burned and its inhabitants slaughtered.

The crusade ran for twenty years, ending with the Treaty of Paris on April 12, 1229. Modern estimates put the total Cathar dead across the period at roughly 200,000. Raphael Lemkin, who in 1944 coined the word genocide, cited the Albigensian Crusade as one of his foundational examples.