Louis VIII's southern campaign against the Albigensians

Timeline

1. 1226Lyon · Auvergne-Rhône-AlpesLouis VIII, in the name of eradicating the Albigensian heresy and with papal support, mobilized the royal army and northern lords, marching south from northern France in spring and summer 1226 into Languedoc, long affected by the Albigensian Crusade.
2. 1226Avignon · Provence-Alpes-Côte d'AzurThe French army besieged and captured Avignon, then continued south to seize several strongholds in Languedoc; Cathar strongholds and local lords' forces suffered heavy blows, and the southern heretical armed forces further disintegrated.
3. c. 1226–1229Montpellier · OccitaniaLouis VIII died of illness at Montpensier at only 39; his son Louis IX was young, with his mother Blanche serving as regent. Though the 1226 southern campaign was cut short by the king's death, it had greatly weakened southern heretics and separatist forces, paving the way for the 1229 Treaty of Paris and royal integration of Languedoc.