The Duchy of Milan is a constituent state of the Holy Roman Empire in northern Italy.

It is created in 1395, when it includes twenty-six towns and the wide rural area of the middle Padan Plain east of the hills of Montferrat.

During much of its existence, it is wedged between Savoy to the west, Venice to the east, the Swiss Confederacy to the north, and separated from the Mediterranean by Genoa to the south.

The Duchy eventually falls to Habsburg Austria with the Treaty of Baden (1714), concluding the War of the Spanish Succession.

The Duchy remains an Austrian possession until 1796, when a French army under Napoleon Bonaparte conquers it, and it ceases to exist a year later as a result of the Treaty of Campo Formio, when Austria cedes it to the new Cisalpine Republic.After the defeat of Napoleon, the Congress of Vienna of 1815 restores many other states which he had destroyed, but not the Duchy of Milan.

Instead, its former territory becomes part of the Kingdom of Lombardy–Venetia, with the Emperor of Austria as its king.

In 1859, Lombardy is ceded to the Kingdom of Piedmont-Sardinia, which will become the Kingdom of Italy in 1861.