Pope Innocent III launched the Albigensian Crusade against the Cathar heresy in Languedoc, southern France, marking the first crusade against fellow Christians. The conflict devastated the region, suppressed the Cathar movement, and established the medieval inquisition. This crusade transformed the relationship between the church and dissenting religious movements, establishing a pattern of persecution that would last for centuries.

The Albigensian Crusade's suppression of the Cathars, who had their own poetic traditions, influenced the development of Occitan lyric poetry and the legend of the troubadours. The crusade's violence and the subsequent inquisition are reflected in the poetry of the period, including the works of the troubadours themselves and later romantic depictions by poets like Dante Gabriel Rossetti.