Capital: Milan City
Official Languages: Lombard, Italian
Established: 1395 AD/CE
Disestablished: 1796 AD/CE
The House of Visconti had ruled Milan since 1277, in which year Ottone Visconti defeated Napoleone della Torre. The Duchy of Milan (Ducatus Mediolani) as a state of the Holy Roman Empire was created on 1 May 1395, when Gian Galeazzo Visconti, purchased a diploma for 100,000 Florins from King Wenceslaus. It was this diploma that installed Visconti as Duke of Milan and Count of Pavia.
The Duchy, as defined in the diploma of 1395, included the territory surrounding Milan, between the Adda and Ticino rivers, but the dominions of Gian Galeazzo Visconti extended beyond, including 26 towns and spanned from Piedmont to Veneto and from present-day Canton of Ticino to Umbria. Milan thus became one of the five major states of the Italian peninsula in the 15th century. The House of Visconti had been expanding their dominions for nearly a century, under the reigns of Azzone Visconti, Luchino Visconti, Giovanni Visconti, Bernabò Visconti and Gian Galeazzo Visconti: during the rule of Azzone Visconti, the Ossola in Piedmont had been conquered in 1331, followed by Bergamo and Pavia (Lombardy) and Novara (Piedmont) in 1332, Pontremoli (Tuscany) in 1333, Vercelli (Piedmont) and Cremona (Lombardy) in 1334, the Lombard cities of Como, Crema, Lodi and the Valtellina in 1335, Bormio (Lombardy) and Piacenza (Emilia) in 1336, and Brescia and the Val Camonica in 1337.
The brothers Luchino and Giovanni Visconti added Bellinzona (present-day Switzerland in 1342, Parma (Emilia) in 1346 and several territories in southwestern Piedmont in 1347: Tortona, Alessandria, Asti, and Mondovì. Bernabò conquered Reggio Emilia in 1371 and Riva del Garda in 1380, and Gian Galeazzo greatly expanded Milan's dominions, first estwards, with the conquest of the Venetian cities of Verona (1387), Vicenza (1387), Feltre (1388), Belluno (1388) and Padova (briefly, from 1388 to 1390), and later southwards, conquering Lucca, Pisa and Siena in Tuscany in 1399, Bologna in Emilia in 1402, and Perugia and Assisi in Umbria also in 1402.
When the last Visconti Duke, Filippo Maria, died in 1447 without a male heir, the Milanese declared the so-called Golden Ambrosian Republic, which soon faced revolts and attacks from its neighbors. In 1450 mercenary captain Francesco Sforza, having previously married Filippo Maria Visconti's illegitimate daughter Bianca Maria, conquered the city and restored the Duchy, founding the House of Sforza.
During the rule of the Visconti and Sforza, the duchy had to defend its territory against the Swiss, the French and the Venetians, until the Betrayal of Novara in 1500 when the duchy passed to the French-claim of Louis XII.
In 1498, the Duke of Orleans became King of France as Louis XII, and immediately sought to make good his father's claim to Milan. He invaded in 1499 and soon ousted Lodovico Sforza. The French ruled the duchy until 1512, when they were ousted by the Swiss, who put Lodovico's son Massimiliano on the throne. Massimiliano's reign did not last very long. The French, now under Francis I, invaded the area in 1515 and reasserted their control at the Battle of Marignano. The French took Massimiliano as their prisoner. The French were again driven out in 1521, this time by the Austrians, who installed Massimiliano's younger brother, Francesco II Sforza.
Following the French defeat at Pavia in 1525, which left the imperial armies of Charles V dominant in Italy, Francesco joined the League of Cognac against the emperor along with Venice, Florence, the Pope, and the French. This resulted quickly in his own expulsion from Milan by imperial forces, but he managed to remain in control of various other cities in the duchy, and was again restored to Milan itself by the peace concluded at Cambrai in 1529.
In 1535, Francesco died without heirs, the question of succession again arose, with both the emperor and the King of France claiming the duchy, leading to more wars. The Duchy of Parma was created in 1545 from a part of the Duchy of Milan south of the Po River, as a fief for Pope Paul III's illegitimate son, Pier Luigi Farnese, centered on the city of Parma.
The emperor Charles V, Holy Roman Emperor held the duchy from 1535, eventually investing it on his son Philip II, King of Spain from 1556. The possession of the duchy by Habsburg Spain was finally recognized by the French in the Treaty of Cateau-Cambrésis in 1559.
The Duchy of Milan remained in Habsburg Spain hands until the War of the Spanish Succession (1701-1714), when the Austrians invaded it (1701) and obtained it with the Convention of Milan in 1707.
The duchy remained in Austrian hands until it was overrun by the French army of Napoleon Bonaparte in 1796. The duchy was ceded by Austria in the Treaty of Campo Formio in 1797, and formed the central part of the new Cisalpine Republic.
After the defeat of Napoleon, based on the decisions of the Congress of Vienna on 9 June 1815, the Duchy of Milan was not restored. The Duchy instead became part of the Kingdom of Lombardy–Venetia, a constituent of the Austrian Empire and with the Emperor of Austria as its king. This kingdom ceased to exist when the remaining portion of it was annexed to the Kingdom of Italy in 1866.