After the peace of Constance, which freed the Lombard Communes from Imperial interference in the year 1183, Milan, by her geographical position, rose rapidly to be the first city of North Italy. Without narrating the changes by which she lost her freedom as a Commune, it is enough to state that, earliest of all Italian cities, Milan passed into the hands of a single family. The Visconti managed to convert this flourishing commonwealth, with all its dependencies, into their private property, ruling it exclusively for their own profit, using its municipal institutions as the machinery of administration, and employing the taxes which they raised upon its wealth for purely selfish ends. When the line of the Visconti ended in the year 1447, their tyranny was continued by Francesco Sforza, the son of a poor soldier of adventure, who had raised himself by his military genius, and had married Bianca, the illegitimate daughter of the last Visconti. On the death of Francesco Sforza in 1466, he left two sons, Galeazzo Maria and Lodovico, surnamed Il Moro, both of whom were destined to play a prominent part in history. Galeazzo Maria, dissolute, vicious, and cruel to the core, was murdered by his injured subjects in the year 1476. His son, Giovanni Galeazzo, aged eight, would in course of time have succeeded to the Duchy, had it not been for the ambition of his uncle Lodovico. Lodovico contrived to name himself as Regent for his nephew, whom he kept, long after he had come of age, in a kind of honourable prison. Virtual master in Milan, but without a legal title to the throne, unrecognised in his authority by the Italian powers, and holding it from day to day by craft and fraud, Lodovico at last found his situation untenable; and it was this difficulty of an usurper to maintain himself in his despotism which, as we shall see, brought the French into Italy.