The Cathar Crusade: Part IV-The Battle of Muret

The Cathar Crusade, a crusade against non-violent followers of a different form of Christianity, lasted from 1209 to 1229, and resulted in the conquest of the Toulouse region by the French king, the establishment of papal domination over the Christian church in Europe and the creation of the Papal Inquisition, basically the first secret police. Part IV covers the failure of Count Raymond of Toulouse to defend his lands against the northern invader simon de Montfort and the attempt by King Pedro of Aragon to use the threat of the crusade to gain influence in the Languedoc, which results in the decisive Battle of Muret.

Cast of Characters:
Simon de Montfort-earl of Leicester, viscount of Trencavel, leader of the crusade 
Raymond VI-Count of Toulouse
Raymond-Roger-Count of Foix
Fulk-Bishop of Toulouse, member of the Cistercian Order
Arnaud Almaric-Cistercian abbot, papal legate
Innocent III-Pope
Pedro II-king of Aragon, count of Barcelona

Sources:
Kill Them All: Cathars and Carnage in the Albigensian Crusade-Sean McGlynn
Innocent III: Leader of Europe 1198-1216-Jane Sayers
Pope Innocent III and His Times-Joseph Clayton
The Popes: A History-John Julius Norwich
The Occitan War: A Military and Political History of the Albigensian Crusade, 1209-1218-Laurence W. Marvin
A Most Holy War: The Albigensian Crusade and the Battle for Christendom-Mark Gregory Pegg
The Perfect Heresy: The Life and Death of the Cathars-Stephen O'Shea
The Albigensian Crusade-Jonathan Sumption
The Medieval Crown of Aragon: A Short History-T. N. Bisson

Image Credit:
Pope Innocent III excommunicating the Albigensians (left). Massacre against the Albigensians by the Crusaders (right). 
By Chroniques de Saint-Denis - http://www.bl.uk/catalogues/illuminatedmanuscripts/ILLUMIN.ASP?Size=mid&IllID=43733, Public Domain, https://commons.wikimedia.org/w/index.php?curid=13305991