The crisis that followed the demise of Gian Galeazzo Visconti at the beginning of the fifteenth century resulted in the murder of his successor, Giovanni Maria Galeazzo, in 1412. At the same time, taking advantage of the situation, Venice started to advance and gain more and more territories in eastern Lombardy.
The crisis was overcome by Gian Galeazzo’s second son, Filippo Maria Visconti, who ruled over Milan from 1412 to 1447. With a very effective financial policy and a strong military effort, he succeeded in reconstituting the duchy and restoring its power.
At his death, due to no direct heirs, a group of aristocrats and intellectuals gave life to the fragile Ambrosian Republic, evoking a restoration of the municipal liberties. At the same time, the other cities of the duchy claimed their independence, while the actual succession was disputed between the Visconti, Savoy, and Sforza.
After long struggles, Francesco Sforza proclaimed himself Duke of Milan, acclaimed by the masses. In 1454, he signed the Peace of Lodi with Venice, and under the Sforza dynasty, Milan and the entire duchy enjoyed a long period of peace in which the capital gained international importance.
The fate of Milan was bound to change once again at the beginning of the sixteenth century when Ludovico Maria Sforza, also known as Ludovico il Moro, came to power. Driven by an ambitious and tortuous policy, Moro favored foreign intervention in the duchy’s affairs, giving Louis XII of France the perfect occasion to occupy the city.