Francesco I Sforza ruled Milan, having acquired the title of Duke of Milan (1450–1466) after marrying in 1441 the natural daughter and only heir of the last Duke of Milan, Filippo Maria Visconti, Bianca Maria (1425–1468), making the Sforzas the heirs of the house of Visconti.. Cosimo de Medici used his network of bank branches across Europe to do more than just make money. During one of the intervals when he got along well with Milan’s duke, he betrothed Visconti’s illegitimate daughter and only child in 1433. Association with Visconti Predecessors. The following year, however, Sforza switched sides and left the duke of Milan’s employ for that of his rival, Cosimo de Medici of Florence. People. Lorenzo’s great-great-grandson Cosimo (1519-1574) became duke of Florence in 1537, then grand duke of Tuscany in 1569. On the duke's death being known to his council, it was debated whether the sovereignty should be offered to Sfor za, or Alphonzo of Arragon. The Sforza hoped to create the appearance of legitimacy in their rule of Milan by linking themselves to the Visconti. Because Francesco married an illegitimate daughter of the last Visconti duke, his progeny carried Visconti blood. Medici cash was spread far and wide to keep him informed about the machinations of Florence’s - and the Medici family’s - enemies. History. Azzone Visconti (1302–1339), lord of Milan; Ennio Quirino Visconti (1751–1818), Italian antiquarian and art historian; Federico Visconti (1617–1693), Cardinal and Archbishop of Milan from 1681 to 1693; Filippo Maria Visconti (bishop) (1721–1801), Archbishop of Milan from 1784 to 1801 Gaspare Visconti (1538–1595), Archbishop of Milan from 1584 to 1595 The latter party had the ma jority, and the first intimation which the citizens of Milan received of the death of Visconti, was the hoisting of … They were also used as an intelligence network.