Milan, February 1450. After years of famine and street riots, the senate did something almost unheard of: it handed a mercenary captain the duchy itself. Francesco Sforza rode into the city on 26 February as duke, turning hired steel into lawful rule.

He had begun far from Milan. Born in 1401 at Cigoli near San Miniato, the illegitimate son of Muzio Sforza, a famous condottiero, he grew up in Tricarico and followed his father into war by 1419. In the campaigns around L'Aquila he learned the trade fast, then served Pope Martin the Fifth and Filippo Maria Visconti, Duke of Milan, rising, falling into prison at Mortara, and climbing back again by force of skill.

By 1431 he was leading Milanese armies against Venice, and Filippo Maria tried to bind him closer by betrothing him to his daughter, Bianca Maria Visconti. Trust never followed. Francesco changed sides when pay and advantage shifted, took Ancona, and won office from Pope Eugene the Fourth. In 1441, at Cremona, the marriage finally took place, sealing a claim to Milan as much as a family alliance.

The hinge came in 1447 when Filippo Maria died without a male heir and Milan became the Ambrosian Republic. Francesco did not rush the walls at once. He gathered Pavia, Lodi, William the Eighth of Montferrat, and once more Venice, then squeezed the republic while hunger did the rest. When revolt shook Milan in 1450, the city chose the man outside its gates.

As duke, he proved he could govern as well as fight. He steadied Milan's finances, reorganised taxation, repaired canals, and founded the Ospedale Maggiore. His closest ally was Cosimo de' Medici, the ruler of Florence, and together they pushed towards the Peace of Lodi in 1454. That settlement, followed by the Italian League, gave the peninsula a rare balance of power and checked the reach of Venice, Naples, and foreign crowns alike.

He still ruled like a soldier. In 1461 he moved on Genoa during a revolt there, setting up Spinetta Campofregoso as doge and then occupying Genoa and Savona by 1464. Edward the Fourth of England sought his friendship and made him a knight of the Order of the Garter in 1463. Yet his body was failing: gout and hydropsy slowed him, and in 1462 rumours of his death even sparked a riot in Milan.

Francesco Sforza died on 8 March 1466, after four more years won against those rumours. His son Galeazzo Maria Sforza succeeded him as Duke of Milan.

The lasting fact is not simply that he fought well. Francesco was among the few condottieri to convert battlefield contracts into a durable state, and the dynasty he founded held Milan for decades. Even Leonardo da Vinci was later asked by Ludovico Sforza, another son, to design his great equestrian monument in Milan, a tribute to the captain who had made himself a prince.