Catharism was the name given to a Christian religious sect that appeared in the Languedoc region of what is now southern France and flourished in the 12th and 13th centuries. The Cathars saw matter as intrinsically evil. They denied that Jesus could become incarnate and still be the son of God and thus, the Catholic Church regarded the sect as dangerously heretical. Faced with what they saw as a rapidly spreading cancer, the Church called for a crusade, which was carried out by knights from Northern France and Germany and was known as the Albigensian Crusade. This campaign, and the inquisition that followed it, eradicated the Cathars completely. It also had the effect of weakening the semi- independent southern principalities in the area, ultimately bringing them under direct control of the King of France.