The Albigensian Crusade was called in 1209 at the apex of the power of the Catholic Church in the Middle Ages. Its aim was to remove the Cathar heresy which previously florished in Southern France, and to bring back to the Catholic Church its believers. In doing so, the Papacy gradually developped the Medieval Inquisition, which burned the last Cathar 'perfect' in 1321. To this date, Historians still lenghly argue on pretty much everything about Cathars : where they came from, what they believed, how they were organized and if they even really existed.