Gautier or Walter V of Brienne was born in Brienne-le-Château, Aube, Champagne, France.
Background
He was the son of Hugh, Count of Brienne and Lecce, and Isabella de la Roche, daughter of Guy I de la Roche, Duke of Athens. He was the heir of the Brienne claim to the Kingdom of Jerusalem and of Cyprus, as well as to Taranto and Sicily. On the death of his father Hugh in 1296, Walter inherited the titles of Count of Brienne, Conversano and Lecce.
Like his father, he took up arms in the service of Naples, but was captured in an ambush at Gagliano in 1300.
Career
Walter spent his youth as a hostage in Sicily, in the castle of Agosta. He was freed in 1302 with the signing of the Treaty of Caltabellotta. There he found himself hard pressed by the Despot of Epirus, the Emperor Andronikos II Palaiologos and the Lord of Vlachia (Thessaly), John II Doukas.
In 1310, he hired the Catalan Company, then ravaging the Byzantine Empire, to fight the Byzantine Greeks encroaching on his territory.
After the Company had successfully reduced his enemies, he attempted to expel the Company from Athens with their pay in arrears. The Company refusing this, Walter marched out with a strong force of French knights from Athens, the Morea and Naples and Greek foot from Athens.
Walter"s army met the Catalans at the Battle of Halmyros (located either near Halmyros in Thessaly or near Orchomenos in Boeotia) on 15 March 1311. The Catalan Company nominated one of the surviving knights, Roger Deslaur, as their leader and new Duke of Athens by conquest.
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, seigneur d"Enghien and claimed her brother"s title to Lecce and Conversano on his death.