Filippo Maria Visconti, Gian Galeazzo’s ten-year-old younger son, becomes nominal ruler of Pavia in 1402.

Francesco Bussone, born at Carmagnola, near Turin, in a humble peasant family, had begun his military career when twelve years old under Facino Cane, a condottiero then in the service of Gian Galeazzo Visconti, duke of Milan.

Carmagnola's success has been astonishingly rapid: he has subdued Bergamo, …

…Brescia, …

…Parma, …

…Genoa, and other cities.

Soon the whole duchy has been brought once more under Visconti's sway, but Filippo Maria, although he rewards Carmagnola generously, fears that he might become a danger to himself, and instead of giving him further military commands makes him governor of Genoa.

The duchy of Milan had been divided among the captains of Facino Cane at his death in 1412, but Gian Galeazzo's son and heir, Filippo Maria, has determined to reconquer it by force of arms.

With Cane dead, Visconti applies to Carmagnola, now in his thirtieth year, and gives him command of the army.

The condottiero Carmagnola deliberately causes the collapse of the Trezzo sull'Adda Bridge, the longest arch bridge in the world at this time, by weakening one of its abutments during a siege in 1416.

Venice, prompted by commercial advantage and the threat of Duke Filippo Maria Visconti, who hopes to retake his father’s conquests of Verona and Vicenza and to rule all of northern Italy, allies itself with Florence against Milan in 1426.

Ferrara, Mantua, Siena, and Savoy soon join the Venetian-Florentine alliance and assemble a large army commanded by Francesco Carmagnola.

Upon the entry of Carmagnola’s forces into Brescia in March, 1426, a prearranged revolt breaks out, aiding the imposition of a siege.

Francesco Sforza, the Milanese defender, surrenders, but reinforcements on both sides enable the fighting to continue for eight months, when the last Milanese stronghold falls, with the help of artillery, in November.

Visconti, under advice by the emperor Sigismund, has refused to ratify the Peace of Venice, on which the ink has barely dried, when he unsuccessfully attempts to ambush and kill Carmagnola at Chiari in 1427.

Failing in his attempt to assassinate Carmagnola, he rearms his Po River fleet and renews warfare in May 1427.

The Milanese are initially victorious, taking Casalmaggiore and …