In 1431, after a period during which he fought again for the Papal States, he led the Milanese army against Venice; the following year the duke's daughter, Bianca Maria, was betrothed to him. Despite these moves, the wary Filippo Maria never ceased to be distrustful of Sforza. The allegiance of mercenary leaders was dependent, of course, on pay; in 1433-1435, Sforza led the Milanese attack on the Papal States, but when he conquered Ancona, in the Marche, he changed sides, obtaining the title of vicar of the city directly from Pope Eugene IV. In 1436-39, he served variously both Florence and Venice.