The Venetians, on the other hand, renewed their treaty with the Catalans in April 1331. Sailing from Brindisi in August, Walter attacked first the Latin County palatine of Cephalonia and Zakynthos, and the Greek Despotate of Epirus, forcing them to recognize the overlordship of King Robert. He also seized the island of Leucas and the mainland castle of Vonitsa for himself in the process. From there he proceeded to invade the Duchy of Athens through northern Boeotia, but his campaign was a failure as the Catalans avoided battle and withdrew behind the walls of Thebes and Athens. Walter had neither the troops to overwhelm the Catalans nor the money to sustain a prolonged war of sieges and attrition, and found no support among the native Greek population. By summer 1332, it was clear that the expedition had failed, and Walter returned to Brindisi, saddled with even more crippling debts. In his new Greek domains of Leucas and Vonitsa, Walter initially appointed a series of French castellans. In 1343, he made the Venetian Graziano Zorzi, who had helped finance his 1331 expedition and joined it himself, governor of Leucas. Zorzi proved successful in this role, and in October 1355, Walter granted Leucas as well as Vonitsa to him as a fief. Ruler of Florence He also occupied himself with his lands in France, and was the King's Lieutenant in Thiérache in 1339. His wife died in 1340, and he returned to Italy in 1342 when the Florentine ruling class of wealthy merchants called upon him to rule the city. Since 1339, Florence had been in the grip of a severe economic crisis brought about by immense English debts to Florentine banking houses, and by astronomical public debts incurred in trying to obtain the nearby city of Lucca from its Veronese lord, Mastino della Scala. The Florentine nobility looked to foreign powers to solve the city's seemingly impossible financial problems, and found an ally in Walter of Brienne. Although the ruling class invited Walter to rule for a limited time, the lower classes, who were fed up with the ineptitude of Walter's predecessors, unexpectedly proclaimed him signore for life. Walter VI ruled despotically, ignoring or directly opposing the interests of the very same merchant class that had brought him to power. The "Duke of Athens" imposed harsh economic correctives on the Florentines, including the flat tax estimo, and prestanze, postponements of the