Victories by the Ghibellines, the imperial family's supporters, forced the Pope to ask Charles to send his troops to Tuscany. Charles' troops ousted the Ghibellines from Florence in April 1267. After being elected the Podestà (ruler) of Florence and Lucca for seven years, Charles hurried to Tuscany. Charles' expansionism along the Papal States's borders alarmed Pope Clement and he decided to change the direction of Charles' ambitions. The Pope summoned him to Viterbo, forcing him to promise that he would abandon all claims to Tuscany in three years. He persuaded Charles to conclude agreements with William of Villehardouin, Prince of Achaea, and the titular Latin Emperor Baldwin II in late May. According to the first treaty, Villehardouin acknowledged Charles' suzerainty and made Charles' younger son, Philip, his heir, also stipulating that Charles would inherit Achaea if Philip died childless. Baldwin confirmed the first agreement and renounced his claims to suzerainty over his vassals in favour of Charles. Charles pledged that he would assist Baldwin in recapturing Constantinople from the Byzantine emperor, Michael VIII Palaiologos, in exchange for one third of the conquered lands.