Milan, Duchy of

a medieval state established around the city of Milan; the city’s ruler, Giangaleazzo Visconti, gained the title of duke in 1395. The duchy disappeared in 1447 upon the death of the last member of the Visconti dynasty and the proclamation of the Ambrosian Republic, but it was restored by the Sforza family in 1450. In 1535, when the last of the Sforzas died, the Duchy of Milan became part of the Spanish possessions in Italy.