Philip Augustus had foreseen this mistake.

After my death," he had said, "the clergy will use all their efforts to entangle my son Louis in the matters of the Albigensians; but he is in weak and shattered health; he will be unable to bear the fatigue; he will soon die, and then the kingdom will be left in the hands of a woman and children; and so there will be no lack of dangers." The prediction was realized.

The military campaign of Louis VIII.

on the Rhone was successful; after a somewhat difficult siege, he took Avignon; the principal towns in the neighborhood, Nimes and Arles, amongst others, submitted; Amaury de Montfort had ceded to him all his rights over his father's conquests in Languedoc; and the Albigensians were so completely destroyed or dispersed or cowed that, when it seemed good to make a further example amongst them of the severity of the Church against heretics, it was a hard matter to rout out in the diocese of Narbonne one of their former preachers, Peter Isarn, an old man hidden in an obscure retreat, from which he was dragged to be burned in solemn state.

This was Louis VIII.'s last exploit in Southern France.