After crossing the territory of his erstwhile employer, Nerio Acciajuoli, Urtubia made for Thebes, the capital of Athens and the chief city of Boeotia. It was a strategic gem, controlling communications between Athens in the south and the Duchy of Neopatria to the north, another Catalan possession. With the support of Niccolò III dalle Carceri, Duke of the Archipelago on his right and Nerio guarding his rear, Urtubia was secure to besiege Thebes for a long time. From the north, too, Francis Zorzi, the Margrave of Bodonitsa, rendered aid against his overlords, the Catalans. The Republic of Venice, which might have stepped in to stop the overtures of Carceri at least, was too involved in the War of Chioggia to be of any help to vulnerable Thebes. Within Thebes, too, disaffected Catalans (mostly those who had supported Frederick III of Sicily against Peter of Aragon in a previous civil war), as well as the majority of Greeks and the archbishop, Simon Atumano, lent tacit support to the besiegers. Finally, Nerio Acciajuoli also lent aid to Urtubia in hopes that he would also conquer Athens.
