Following the death of Filippo Maria Visconti, who had ruled the Duchy of Milan from 1412 until his death in 1447, Cosimo sent Francesco I Sforza to establish himself in Milan to prevent an impending military advance from the Republic of Venice. Francesco Sforza was a "condottiere", a mercenary soldier who had stolen land from the papacy and proclaimed himself its lord. He had yearned to establish himself at Milan as well, an ambition that was aided by the fact that the current Visconti head lacked legitimate children save for a daughter, Bianca, whom Sforza ultimately married in November 1441 after a failed attempt at winning her hand from her father. The resultant balance of power with Milan and Florence on the one side and Venice and the Kingdom of Naples on the other created nearly half a century of peace that enabled the development of the Renaissance in Italy. However, despite the benefits to Florence from keeping Venice at bay, the intervention in Milan was unpopular among Cosimo's fellow citizens, primarily because they were called upon to finance the Sforza succession. The Milanese made a brief attempt at democracy before Sforza was finally acclaimed duke by the city in February 1450.