From the initial congregation of cities subject to the dominion of a single lord, Giovanni and Luchino but above all Gian Galeazzo and Bernabò, through an intense activity of consolidation of their supremacy implemented with the downsizing of local autonomies and the attraction in their orbit of the many small rural lordships created a sort of state structure.
With Giovanni Visconti, in the mid-fourteenth century there was the first major expansion of the family's possessions with the victory over the Lords of Verona (the Scaligeri) and with the submission of even Genoa and Bologna.
Some see, however, in the Visconti - especially after the death of Archbishop Giovanni Visconti in 1354 - the typical example of the tyrant with special regard to Bernabò, his nephew Gian Galeazzo and the son of these Giovanni Maria. It should not be overlooked, however, that the first two contributed to a considerable extension of the Duchy of Milan and Gian Galeazzo succeeded in obtaining the title of duke in 1395 by Emperor Wenceslas.
After the death of Gian Galeazzo in 1402 the Duchy - which had reached its maximum expansion - passed to his sons Giovanni Maria (who died in 1412) and Filippo Maria (who died in 1447), but the dominion, which Gian Galeazzo had put together with all sorts of violence, shattered, and barely the oldest provinces that composed it could be preserved.
The Ducal line of Milan became extinct in the men's line with the death of Filippo Maria in 1447 and the Duchy passed (after the brief experience of the Ambrosian Republic) to Francesco Sforza, who had married Filippo's illegitimate daughter, Bianca Maria. In the legitimate feminine line, the Valois-Orleans, as descendants of Valentina Visconti, boasted serious rights over Milan, rights that were enforced by Louis XII of France in the early sixteenth century.