House of Visconti
With the death of Filippo Maria, the House of Visconti lost power. For a short time the area was transformed into the Ambrosian Republic (1447–50), until Milan capitulated to Francesco Sforza, who became Duke of Milan and Lombardy. Bellagio, whose territory (and especially the fortress) was occupied by the troops of Sforza in 1449 during the war of succession, was one of the first towns on the lake to take sides and adhere to Sforza rule.