County of Brienne. Walter landed at Glarentza in Achaea in the summer of 1309. By the time he reached Athens, John II Doukas, ruler of Thessaly, had got rid of Athenian suzerainty. The Byzantine emperor Andronikos II Palaiologos, and the actual ruler of Epirus, Anna Palaiologina Kantakouzene, supported John II, forcing Walter to seek external assistance. The Catalan Companya group of unemployed mercenarieshad made regular raids against Thessaly since 1305. Walter hired the Catalans and their Turkish allies to fight against the Greek rulers. The mercenaries invaded Thessaly and occupied important fortresses. After six months, John II was forced to sue for peace. Walter owed the mercenaries four months' salaries, but he did not want to pay the arrears. He selected 200 horsemen and 300 almogàvars (lightly-armed foot soldiers) from among the Catalans and promised only to them to pay their wages. He also offered fiefs to them and ordered all other Catalans to leave the duchy. The dismissed mercenaries refused to move and requested Walter to allow them to settle in the newly conquered lands as his vassals. Walter did not trust the Catalans and threatened them with capital punishment if they did not obey his commands. Having nowhere else to go, the disbanded mercenaries rose up in open rebellion. The 500 Catalan mercenaries whom Walter had just hired joined their compatriots, forcing Walter to seek assistance from Achaea and other parts of Frankish Greece. Walter's army met the Catalans in a marshy plain at Halmyros on 15 March 1311. The Catalans were willing to make peace, but Walter was determined to get rid of them. At the ensuing Battle of Halmyros, the Catalans won a devastating victory, killing Walter and almost all of his cavalry. The Catalans occupied the Duchy of Athens, and Walter's son, who was taken to Italy after the Catalans' victory, made unsuccessful attempts to regain it in the following decades. A Turkish soldier decapitated Walter's corpse and took his head in triumph from the battlefield. His son seized Walter's severed head and buried it in Lecce, most probably in the church of Sant'Oronzo, in 1348. Genealogical table In the year 1306 he married Jeanne de Châtillon and had two children: Walter VI of Brienne (1302–1356), his successor as count of Lecce and Conversano, as well as the titular duke of Athens Isabella of Brienne (died 1360), married Gautier III, lord of Enghien, and claimed