Louis VIII of France
Along with his brother Peter, Duke of Brittany he fought with future Louis VIII of France in 1212 at Nantes and was captured there during a sortie. Exchanged after the Battle of Bouvines for William Longsword, Earl of Salisbury, he fought in the Albigensian Crusade, besieging Avignon in 1226. He was a supporter of Blanche of Castile during her regency after the death of Louis VIII in 1226.