only after he ceded Walter as a hostage to the Aragonese admiral, Roger of Lauria, to guarantee the payment of his ransom. Walter was kept in the fortress at Augusta for years. He most probably learnt Catalan and became familiar with the Aragonese customs during the years of his captivity. Walter was still held in custody when his father died fighting against Lauria at Brindisi in the summer of 1296. King Charles II ordered Hugh's southern Italian vassals to swear fealty to Walter on 27 August. After being released, Walter went to France and took possession of his father's French domains. He was invested with the County of Brienne before May 1297. Warlike aristocrat Seeking revenge for his father's death, Walter made an alliance with two French noblemen whose fathers had also been murdered in Italy. They hired 300 horsemen, who were known as the "Knights of Death", and joined the army that Charles II's heir, Robert, Duke of Calabria, had mustered to invade Sicily. Robert and his troops landed at Catania and occupied the town. Before long, rumours reached the Neapolitan camp, hinting that the castellan of Gagliano Castelferrato was willing to capitulate without resistance. Robert dispatched Walter and his retainers to the fortress to start negotiations with the castellan. The rumours proved false, deliberately spread to trap Neapolitan troops. After realizing the situation, Walter refused to flee and did battle against the Aragonese troops, but he was soon forced to surrender. Charles II appointed Philip of Toucy to administer Walter's southern Italian domains during his captivity. After the Treaty of Caltabellotta was signed in 1302, ending the War of the Sicilian Vespers, Walter was released. He went to France before June 1303. His subsequent marriage to Joanna of Châtillon, the daughter of the constable of France, strengthened his position in France. Duke of Athens On 5 October 1308, the duke of Athens, Guy II, died childless. His two cousins, Walter and Eschiva of Ibelin, laid claim to the duchy. Eschiva was the daughter of Alice de la Roche, who was the elder sister of Walter's mother, but the High Court of the Principality of Achaea—the feudal suzerain of Athens—ruled in Walter's favor, saying that the male claimant was to be preferred against a female if two relatives of equal degree claimed an inheritance. Before departing for Athens, Walter appointed his father-in-law, Gaucher V de Châtillon, to administer the