The short-lived Ambrosian Republic of Milan (1447 – 1450) was declared upon the death of the last of the Visconti dukes of Milian, Filippo Maria Visconti, in a sanguine moment hopeful of reviving the medieval rights of the comune, and named for St. Ambrose, the 4th century bishop of Milan, who was taken on as the Republic's patron. The citizens of Milan stormed the Visconti castle at the heart of the city and sacked it; by order of the Republic it was demolished. (The present Castello Sforzesco was immediately rebuilt at the site by Francesco Sforza, when he became duke). Visconti was a noble family that ruled Milan during the Middle Ages and Early Renaissance period. ... Filippo Maria Visconti Filippo Maria Visconti, (1392–1447), who became nominal ruler of Pavia in 1402, succeeded his assassinated brother Gian Maria Visconti as Duke of Milan. ... In Italy, the commune (comune, plural comuni) is the basic administrative unit of both provinces and regions, and may be properly approximated in casual speech by the English word township. ... Saint Ambrose, Latin Sanctus Ambrosius, Italian SantAmbrogio (circa 340 - April 4, 397), bishop of Milan, was one of the most eminent fathers of the Christian church in the 4th century. ...

The idea of a radical renovation of liberties in the cities did not suit the powers of North Italy, who had been in league against the Visconti territorial gains in a decades-long series of wars interrupted by truces, most recently the Peace of Cremona of November 20, 1441. Francesco Sforza, the condottiere first for Venice, then for the Visconti, who had married the natural daughter of Filippo Maria, laid siege to Republican Milan, choosing for his headquarters the Borromeo castle at La Peschiera, south-east of the city. Once again he had Venetian-paid forces behind him. The Milanese suffered from internal dissension; there was a coup engineered by the grandi of the city in February 1450, the city surrendered and Sforza entered Milan triumphantly in May, had himself declared capitano del popolo, and thus made himself master of Milan, and by right of his wife, its duke. Portrait of Francesco Sforza, ca 1460, by Bonifazio Bembo: Sforza insisted on being shown in his worn dirty old campaigning hat. ... Condottieri were mercenary leaders employed by Italian city-states from the late Middle Ages until the mid-fifteenth century. ...

The Sforza rights to the Duchy were unsuccessfully challenged by Charles, Duke of Orléans, whose mother Valentine Visconti was Duke Filippo Maria's sister, so the kingdom of Naples joined the Venetians. Two coalitions were now formed, Sforza Milan with Medici Florence on the one hand, against Venice and Aragonese Naples on the other. The continued war was finally closed by the peace of Lodi in 1454 [1] (http://www.veneto.org/history/serenissima3.htm).
The Medici family was a powerful and influential Florentine family from the 13th to 17th century. ...

Filippo Maria Visconti Filippo Maria Visconti, (1392–1447), who became nominal ruler of Pavia in 1402, succeeded his assassinated brother Gian Maria Visconti as Duke of Milan. ... Portrait of Francesco Sforza, ca 1460, by Bonifazio Bembo: Sforza insisted on being shown in his worn dirty old campaigning hat. ...