The matter of heresy in the Catholic Church threatened the unity of Christendom precisely at the time that the pope was calling for an all-out war to reclaim the Holy Lands from the Muslims. Pope Innocent III conceived of the plan to wipe out the Albigensian heresy in the south of France in the early decades of the 13th century. He would call for a crusade.
At first the plan seemed ingenious: The pope would grant to fighters the spiritual benefits of a crusade, but the time of service would be brief (40 days) and close to home in comparison to earlier wars in the Holy Land. His ultimate goal was to unify Europe under papal authority so that he could marshal its resources into the Byzantine Empire, Muslim Spain, and, most important, the Holy Land.
However, the twists and turns in the politics of the Albigensian Crusade (1208–29) ultimately drained resources from the wars abroad and strengthened the anti-Roman forces in France. In the next centuries the blunder of the Albigensian Crusade would be apparent in the schism of Avignon, where a French pope would oppose a Roman pope.
Innocent at first supported the work of preaching and persuasion to win back the Albigensians, a loose network of sectarians and heretics of southern France. A variety of church investigators, from Bernard of Clairvaux to the pope, readily admitted that Catholic clergy serving the Albigensian natives stood in grave need of reform. But when peaceful measures did not make speedy enough progress, Innocent lost patience and turned to war.
His decision came in 1208 when the papal delegate was murdered in Toulouse. Innocent held Count Raymond of Toulouse accountable both for his death and for the protection of the heretics in southern France and summoned the rest of France to take up arms. Some 20,000 knights and 200,000 foot soldiers responded.
Their leader was the crusader veteran Simon de Montfort. Raymond lost no time in making peace with the papal forces, but Simon could never conquer the whole area of the Albigensians. Resistance was too entrenched, and Simon could only count on French troops for 40 days at a time, the terms of service that the church allowed for this crusade. Also, Simon was an outsider and extremely unpopular because of his brutality in war.
In 1213 Innocent seemed to recognize the folly of the crusade and called it off. The king of Aragon, a warrior renowned for his battlefield skills against Muslims in Spain, took up the cause of Raymond. In effect, the Albigensian conflict became a tug of war between Spain and France. Although the pope now supported Raymond, the French nobles supported Simon.
In the political melee that followed, another crusade was summoned. Though it was nominally against heresy, it was really against Raymond and his Spanish allies. On the battlefield the French-backed forces defeated the Spanish-backed forces. Simon’s shocking brutality led to his excommunication by Innocent. He died in battle in Toulouse in 1218. His nemesis Raymond died in 1222.
The Albigensians rebounded throughout these latter years, leading many Catholic and French officials to threaten yet another crusade. Raymond’s son, however, was able to negotiate the Treaty of Meaux (1229), ceding the territory to Capetian France and institutionalizing Catholic influence everywhere. The church meanwhile found a new weapon to combat latent heresy: the Inquisition.