The 2 July 1214, he fought alongside the future King of France,
Louis VIII at the
Battle of Roche-au-Moines, which saw a French victory, thanks to the decisive action of his father-in-law, Guillaume des Roches against the English troops of "Jean sans Terre"
John, King of England. By November 1218, Amaury had arrived in Toulouse with an army as part of the
Albigensian Crusade. He argued with
Simon de Montfort as to the disposition of the army and instead of marching the army to the
siege of Toulouse, per Montfort's wishes, the army encamped in "New Toulouse". During the siege of Toulouse, Amaury and numerous other nobles openly criticized Montfort's tactics. The siege was lifted a month later following the death of Montfort. In 1222, following the death of Guillaume des Roches, Amaury took the title of sénéchal of Anjou, Maine and Touraine. He was thus confronted with the pretension of
Pierre Mauclerc, Peter I, Duke of Brittany, who had his sights on Anjou. In 1223, he seized
Châteaubriant and
La Guerche-de-Bretagne belonging to the domain of
Pouancé, but he could not take the
Castle of Pouancé. Alerted, Pierre Mauclerc came to the rescue and surprised Amaury's exhausted troops. Routed, Amaury was taken prisoner. A large ransom was demanded from his subjects for his liberation. Freed the same year, Amaury rejoined the new King Louis VIII at
Compiègne. ==Death and succession==