How Cosimo de’ Medici Became the Grand Duke of Tuscany

By William Landon, Northern Kentucky University

In 1537, at the time of his elevation to the head of the Florentine government, Cosimo de’ Medici was only 18 years old. His mother was half Medici—the granddaughter of Lorenzo the Magnificent. Cosimo, though quite young, was wise and ruthless beyond his years. Even so, as he became the de facto leader of Florence, he lacked a formal title. Only Charles V could invest Cosimo with the title of duke, and he was not yet prepared to take such an action.

Attempt to Ouster the Medici

The exiled Florentine republicans thought that they might be able to negotiate a reasonable settlement with Cosimo, wherein they might be permitted to return to Florence. A brilliant humanist named Donato Giannotti was assigned the dubious task of seeking an audience with the young Medici. Cosimo agreed to hear Giannotti’s proposals, but refused to negotiate with the republicans who were harboring his cousin’s assassin, Lorenzino.

After Giannotti’s failure, Filippo Strozzi was selected to lead a hastily roused army to attack Florence and relieve it of its Medici tyrants. Against this background of revolution, Lorenzo di Filippo Strozzi, Filippo’s elder brother, wrote to him; attempting to persuade Filippo to retire quietly to the countryside, as Lorenzo had done.

Filippo would have none of it. He and his republican army would either oust the Medici from power or give their lives trying.

This article comes directly from content in the video series How the Medici Shaped the Renaissance. Watch it now, on Wondrium.

How Cosimo Became the Duke

In late July of 1537, the republican army marched into Tuscany. The Medici’s forces met at Montemurlo, about 15 miles to the north of Florence, on August 1, 1537. The republicans were demolished. Those who survived fled into permanent exile. After this scourging of the republicans at Montemurlo, Charles V, in September of 1537, gave Cosimo the title of ‘Duke’.

Filippo Strozzi was captured and transferred to the new Fortezza da Basso and imprisoned. Lorenzino de’ Medici himself was hunted down and murdered over a decade later by bounty hunters in the employ of Cosimo de’ Medici.

Lorenzo remained a social outcast for his support of the Florentine Republic. He began an unrequited correspondence with Cosimo de’ Medici—hoping against all reason that he might secure Filippo’s release. Documentary evidence doesn’t reveal whether Cosimo responded to Lorenzo Strozzi’s long and heartfelt plea, but the official line was that Filippo Strozzi committed suicide, by nearly decapitating himself in his prison cell.

Similarities with Lorenzo the Magnificent

Cosimo was anything but patient. His precocious personality, combined with his tendency toward authoritarianism, was direct, cunning and quick. And he set about solidifying his rule in Florence.

Florence had seen a similar upheaval long ago under Lorenzo the Magnificent’s rule. He had consolidated his power in the aftermath of the Pazzi conspiracy. While he managed to wrest the reins of power from the republican government, in practice it continued to be a part of the tapestry of the city’s daily life and culture—and it was restored after his death, and after Piero the Unfortunate’s flight into exile. 

But Cosimo’s despotism, in comparison, was brazen. He ruled Florence openly as a prince. The question remained, however, what form of despotism would Cosimo’s tenure take—would it be benign or tyrannical?

A Patron of the Arts

Cosimo had built and commissioned the decorations of some of Florence’s most iconic buildings. Case in point—the Uffizi.

Today, as a museum, the Uffizi, is home to one of the largest and finest collections of Renaissance artwork in the world. But when Cosimo de’ Medici commissioned Giorgio Vasari to design and oversee the construction of the uffizi—or ‘offices’—of his government, the building was reserved for the business of Florence and its Medici government.

The florins that Cosimo invested in these construction project enriched not only the visual aesthetic of Florence but also the guild members he employed.

Consolidating Florence’s Position

Outside of Florence, Cosimo set about consolidating the city’s position as the capital of Tuscany. He interacted shrewdly with Emperor Charles V (and his successor Philip II), illustrating that neither he nor Florence were to be considered imperial vassals. For example, at Charles’s behest, Cosimo and his army besieged and took Siena.

Cosimo had managed to reposition Florence’s international alliances away from France—a former alliance that had resulted in Florentine isolation in the previous decades—and he had also managed to gain independence, at least to a degree, from the empire.

This independence was codified by Pope Pius V in 1569, with the blessing of Charles V’s son, Philip II, when Cosimo was granted the title ‘Grand Duke of Tuscany’. At long last, Cosimo and his offspring had become territorial, hereditary princes.

Declining Health

Cosimo, who was known for his impressive physique and height—he was over six feet tall, a rarity for the time—had, as early as late 1550s, begun to decline physically, one suspects due to his physical and martial lifestyle.

His health deteriorated much faster in 1562, after the death of his wife, Eleanor of Toledo. Exhaustion and sadness ruined him. They had had a long, happy, and faithful marriage, one which also produced numerous heirs—the eldest of which, Francesco, was prepared by his father to rule Tuscany.

In 1564, Cosimo abdicated his throne to Francesco, but he remained the force behind the Medici family’s power. And when Cosimo granted Francesco the title, Grand Duke of Tuscany in 1569, he was permitted to inherit that title upon his father’s death.

Common Questions about How Cosimo de’ Medici Became the Grand Duke of Tuscany

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