Béziers was a Languedoc stronghold of Catharism, which the Catholic Church condemned as heretical and which Catholic forces extirpated in the Albigensian Crusade. Béziers was the first city to be sacked, on July 22, 1209.
Arnaud, the Cistercian abbot-commander, is supposed to have been asked how to tell Cathars from Catholics. His alleged reply, recalled by a fellow Cistercian, was "Caedite eos. Novit enim Dominus qui sunt eius." — "Kill them all, the Lord will recognise His own." The doors of the church of St Mary Magdalene were broken down and the refugees dragged out and slaughtered. Reportedly, 7,000 people died there including many women and children. Elsewhere in the town many more thousands were mutilated and killed. Prisoners were blinded, dragged behind horses, and used for target practice. What remained of the city was razed by fire. Arnaud wrote to Pope Innocent III, "Today your Holiness, twenty thousand heretics were put to the sword, regardless of rank, age, or sex.