Pope Innocent III declares a crusade against the Languedoc region of southern France, stronghold of the heretical Cathar christian sect.
Some 10,000 crusaders, led by Simon de Monfort attack the city of Beziers. Its population of about 10,000 is massacred. Abbot Arnaud-Amaury is recorded as saying, “Slay them all! God will know his own.”
Citizens of Minerve surrender to the crusaders. Those willing to convert were allowed to do so but the 140 who refused are burned at the stake.
The crusade is renewed.
April 12, 1229
A peace treaty formally ends
the Albigensian Crusade, although fighting continues for many years.
The Inquisition is established to search out and eliminate the Cathars hiding in the Languedoc region.
Montsegur, the largest remaining Cathar stronghold, falls after a nine month siege.
The last Cathar stronghold, an isolated fort at Quéribus, is captured.