Simon de Montfort, 5th Earl of Leicester (c.1175 25 June 1218), known as Simon IV (or V) de Montfort and as Simon de Montfort the Elder, was a French nobleman and knight of the early 13th century. He is widely regarded as one of the great military commanders of the Middle Ages. He took part in the Fourth Crusade and was one of the prominent figures of the Albigensian Crusade. Montfort is mostly noted for his campaigns in the latter, notably for his triumph at Muret. He died at the Siege of Toulouse in 1218. He was lord of Montfort-l'Amaury from 1188 to his death and Earl of Leicester in England from 1204. He was also Viscount of Albi, Bziers and Carcassonne from 1213, as well as Count of Toulouse from 1215.



The Albigensian Crusade or the Cathar Crusade (1209–1229; French: Croisade des albigeois, Occitan: Crosada dels albigeses) was a 20-year military campaign initiated by Pope Innocent III to eliminate Catharism in Languedoc, in southern France. The Crusade was prosecuted primarily by the French crown and promptly took on a political aspect, resulting in not only a significant reduction in the number of practising Cathars, but also a realignment of the County of Toulouse in Languedoc, bringing it into the sphere of the French crown, and diminishing both Languedoc's distinct regional culture and the influence of the counts of Barcelona.

The Cathars originated from an anti-materialist reform movement within the Bogomil churches of the Balkans calling for what they saw as a return to the Christian message of perfection, poverty and preaching, combined with a rejection of the physical to the point of starvation. The reforms were a reaction against the often perceived scandalous and dissolute lifestyles of the Catholic clergy in southern France. Their theology, neo-Gnostic in many ways, was basically dualist. Several of their practices, especially their belief in the inherent evil of the physical world, conflicted with the doctrines of the Incarnation of Christ and Catholic sacraments. This led to accusations of Gnosticism and attracted the ire of the Catholic establishment. They became known as the Albigensians, because there were many adherents in the city of Albi and the surrounding area in the 12th and 13th centuries.

Between 1022 and 1163, the Cathars were condemned by eight local church councils, the last of which, held at Tours, declared that all Albigenses should be put into prison and have their property confiscated. The Third Lateran Council of 1179 repeated the condemnation. Innocent III's diplomatic attempts to roll back Catharism were met with little success. After the murder of his legate Pierre de Castelnau in 1208, and suspecting that Raymond VI, Count of Toulouse was responsible, Innocent III declared a crusade against the Cathars. He offered the lands of the Cathar heretics to any French nobleman willing to take up arms.

From 1209 to 1215, the Crusaders experienced great success, capturing Cathar lands and systematically crushing the movement. From 1215 to 1225, a series of revolts caused many of the lands to be regained by the Cathars. A renewed crusade resulted in the recapturing of the territory and effectively drove Catharism underground by 1244. The Albigensian Crusade had a role in the creation and institutionalization of both the Dominican Order and the Medieval Inquisition. The Dominicans promulgated the message of the Church and spread it by preaching the Church's teachings in towns and villages in order to stop the spread of alleged heresies, while the Inquisition investigated people who were accused of teaching heresies. Because of these efforts, all discernible traces of the Cathar movement were eradicated by the middle of the 14th century. Many historians consider the Albigensian Crusade against the Cathars an act of genocide.