Cosimo I de' Medici (12 June 1519 – 21 April 1574) was the second
Duke of Florence from 1537 until 1569, when he became the first
Grand Duke of Tuscany
The rulers of Tuscany varied over time, sometimes being margraves, the rulers of handfuls of border counties and sometimes the heads of the most important family of the region.
Margraves of Tuscany, 812–1197 House of Boniface
:These were origin ...
, a title he held until his death.
Life
Rise to power
Cosimo was born in
Florence
Florence ( ; it, Firenze ) is a city in Central Italy and the capital city of the Tuscany region. It is the most populated city in Tuscany, with 383,083 inhabitants in 2016, and over 1,520,000 in its metropolitan area.Bilancio demografico ...
on 12 June 1519, the son of the famous
condottiere Ludovico de' Medici (known as
Giovanni delle Bande Nere) and his wife
Maria Salviati
Maria Salviati (17 July 1499 – 29 December 1543) was a Florentine noblewoman, the daughter of Lucrezia di Lorenzo de' Medici and Jacopo Salviati. She married Giovanni delle Bande Nere and was the mother of Cosimo I de Medici. Her husband died ...
, herself a granddaughter of
Lorenzo the Magnificent. He was the grandson of
Caterina Sforza
Caterina Sforza (1463 – 28 May 1509) was an Italian noblewoman, the Countess of Forlì and Lady of Imola, firstly with her husband Girolamo Riario, and after his death as a regent of her son Ottaviano. Caterina was a noblewoman who lived a ...
, the Countess of Forlì and Lady of
Imola
Imola (; rgn, Jômla or ) is a city and ''comune'' in the Metropolitan City of Bologna, located on the river Santerno, in the Emilia-Romagna region of northern Italy. The city is traditionally considered the western entrance to the historical r ...
. Cosimo came to power in 1537 at age 17, just after the 26-year-old Duke of Florence,
Alessandro de' Medici
Alessandro is both a given name and a surname, the Italian form of the name Alexander. Notable people with the name include:
People with the given name Alessandro
* Alessandro Allori (1535–1607), Italian portrait painter
* Alessandro Baricc ...
, was assassinated. Cosimo was from a different branch of the Medici family, descended from
Giovanni il Popolano, the great-grandson of
Giovanni di Bicci de' Medici, founder of the
Medici Bank
The Medici Bank (Italian: ''Banco dei Medici'' ) was a financial institution created by the Medici family in Italy during the 15th century (1397–1494). It was the largest and most respected bank in Europe during its prime. There are some estim ...
. It was necessary to search for a successor outside of the "senior" branch of the Medici family descended from
Cosimo di Giovanni de' Medici, since the only male child of Alessandro, the last
lineal descendant
A lineal descendant, in legal usage, is a blood relative in the direct line of descent – the children, grandchildren, great-grandchildren, etc. of a person. In a legal procedure sense, lineal descent refers to the acquisition of estate by i ...
of the senior branch, was born
out-of-wedlock and was only four years' old at the time of his father's death.

Up to the time of his
accession, Cosimo had lived only in
Mugello (the ancestral homeland of the
Medici family
The House of Medici ( , ) was an Italian banking family and political dynasty that first began to gather prominence under Cosimo de' Medici, in the Republic of Florence during the first half of the 15th century. The family originated in the Mu ...
) and was almost unknown in Florence. However, many of the influential men in the city favoured him as the new duke. Several hoped to rule through him, thereby enriching themselves at the state's expense. However, as the Florentine
literatus Benedetto Varchi
Benedetto Varchi (; 1502/15031565) was an Italian humanist, historian, and poet.
Biography
Born in Florence to a family that had originated at Montevarchi, he frequented the neoplatonic academy that Bernardo Rucellai organized in his garden, ...
famously put it, "The innkeeper's reckoning was different from the glutton's." Cosimo proved strong-willed, astute and ambitious and soon rejected the clause he had signed that entrusted much of the power of the Florentine duchy to a Council of Forty-Eight.
When the Florentine exiles heard of the death of Alessandro, they marshalled their forces with support from
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...
and from disgruntled neighbors of Florence. During this time, Cosimo had an illegitimate daughter,
Bia (1537 – 1542), who was portrayed shortly before her premature death in a painting by
Bronzino
Agnolo di Cosimo (; 17 November 150323 November 1572), usually known as Bronzino ( it, Il Bronzino ) or Agnolo Bronzino, was an Italian Mannerist painter from Florence. His sobriquet, ''Bronzino'', may refer to his relatively dark skin or red ...
.
Toward the end of July 1537, the exiles marched into Tuscany under the leadership of
Bernardo Salviati and
Piero Strozzi. When Cosimo heard of their approach, he sent his best troops under
Alessandro Vitelli to engage the enemy, which they did at
Montemurlo. After defeating the exiles' army, Vitelli stormed the fortress, where Strozzi and a few of his companions had retreated to safety. It fell after only a few hours, and Cosimo celebrated his first victory. The prominent prisoners were subsequently beheaded on the
Piazza della Signoria
Piazza della Signoria () is a w-shaped square in front of the Palazzo Vecchio in Florence, Italy. It was named after the Palazzo della Signoria, also called Palazzo Vecchio. It is the main point of the origin and history of the Florentine Republ ...
or in the
Bargello
The Bargello, also known as the Palazzo del Bargello, Museo Nazionale del Bargello, or Palazzo del Popolo (Palace of the People), was a former barracks and prison, now an art museum, in Florence, Italy.
Terminology
The word ''bargello'' appears ...
.
Filippo Strozzi's body was found with a bloody sword next to it and a note quoting
Virgil
Publius Vergilius Maro (; traditional dates 15 October 7021 September 19 BC), usually called Virgil or Vergil ( ) in English, was an ancient Roman poet of the Augustan period. He composed three of the most famous poems in Latin literature: t ...
, but many believe that his suicide was faked.
Rule of Tuscany
In 1537, Cosimo sent
Bernardo Antonio de' Medici
Bernardo Antonio de' Medici (1476 – 1552) was an Italian bishop and diplomat. He was considered one of the leading ambassadors of Cosimo I de' Medici.
He was the son of Antonio de' Medici and Selvaggia di Felice del Beccuto. He was bishop of F ...
to Holy Roman Emperor
Charles V Charles V may refer to:
* Charles V, Holy Roman Emperor (1500–1558)
* Charles V of Naples (1661–1700), better known as Charles II of Spain
* Charles V of France (1338–1380), called the Wise
* Charles V, Duke of Lorraine (1643–1690)
* Infant ...
to gain recognition for his position as head of the Florentine state. That recognition came in June 1537 in exchange for help against France in the course of the
Italian Wars
The Italian Wars, also known as the Habsburg–Valois Wars, were a series of conflicts covering the period 1494 to 1559, fought mostly in the Italian peninsula, but later expanding into Flanders, the Rhineland and the Mediterranean Sea. The pr ...
. With this move, Cosimo firmly restored the power of the
Medici
The House of Medici ( , ) was an Italian banking family and political dynasty that first began to gather prominence under Cosimo de' Medici, in the Republic of Florence during the first half of the 15th century. The family originated in the Muge ...
, who thereafter ruled
Florence
Florence ( ; it, Firenze ) is a city in Central Italy and the capital city of the Tuscany region. It is the most populated city in Tuscany, with 383,083 inhabitants in 2016, and over 1,520,000 in its metropolitan area.Bilancio demografico ...
until the death of the last of the Medici rulers,
Gian Gastone de' Medici
Gian Gastone de' Medici (born Giovanni Battista Gastone; 24 May 1671 – 9 July 1737) was the seventh and last Medicean Grand Duke of Tuscany.
He was the second son of Grand Duke Cosimo III and Marguerite Louise d'Orléans. His sister, Electr ...
, in 1737. The help granted to Charles V allowed him to free Tuscany from the Imperial garrisons and to increase as much as possible its independence from the overwhelming Spanish influence in Italy.
Cosimo next turned his attention to
Siena
Siena ( , ; lat, Sena Iulia) is a city in Tuscany, Italy. It is the capital of the province of Siena.
The city is historically linked to commercial and banking activities, having been a major banking center until the 13th and 14th centur ...
. With the support of Charles V, he defeated the Sienese at the
Battle of Marciano
The Battle of Marciano (also known as the Battle of Scannagallo) occurred in the countryside of Marciano della Chiana, near Arezzo, Tuscany, on August 2, 1554, during the Italian War of 1551. The battle marked the defeat of the Republic of Sie ...
in 1554 and laid siege to their city. Despite the inhabitants' desperate resistance, the city fell on 17 April 1555 after a 15-month siege, its population diminished from forty thousand to eight thousand. In 1559,
Montalcino, the last redoubt of Sienese independence, was annexed to Cosimo's territories. In 1569,
Pope Pius V
Pope Pius V ( it, Pio V; 17 January 1504 – 1 May 1572), born Antonio Ghislieri (from 1518 called Michele Ghislieri, O.P.), was head of the Catholic Church and ruler of the Papal States from 8 January 1566 to his death in May 1572. He is v ...
elevated him to the rank of Grand Duke of Tuscany.
In the last 10 years of his reign, struck by the death of two of his sons by
malaria
Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or deat ...
, Cosimo gave up active rule of the Florentine state to his son and successor
Francesco I. He retreated to live in his villa, the
Villa di Castello, outside Florence.
Statesmanship

Cosimo was an authoritarian ruler and secured his position by employing a guard of Swiss
mercenaries
A mercenary, sometimes also known as a soldier of fortune or hired gun, is a private individual, particularly a soldier, that joins a military conflict for personal profit, is otherwise an outsider to the conflict, and is not a member of any ...
. In 1548, he managed to have his relative
Lorenzino, the last Medici claimant to Florence who had earlier arranged the assassination of Cosimo's predecessor Alessandro, assassinated himself in
Venice
Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto region. It is built on a group of 118 small islands that are separated by canals and linked by over 400 bridges. The isla ...
.
Cosimo also was an active builder of military structures, as a part of his attempt to save the Florentine state from the frequent passage of foreign armies. Examples include the new fortresses of Siena,
Arezzo
Arezzo ( , , ) , also ; ett, 𐌀𐌓𐌉𐌕𐌉𐌌, Aritim. is a city and ''comune'' in Italy and the capital of the Province of Arezzo, province of the same name located in Tuscany. Arezzo is about southeast of Florence at an elevation o ...
,
Sansepolcro
Sansepolcro, formerly Borgo Santo Sepolcro, is a town and ''comune'' founded in the 11th century, located in the Italian Province of Arezzo in the eastern part of the region of Tuscany.
Situated on the upper reaches of the Tiber river, the town ...
, the new walls of
Pisa
Pisa ( , or ) is a city and ''comune'' in Tuscany, central Italy, straddling the Arno just before it empties into the Ligurian Sea. It is the capital city of the Province of Pisa. Although Pisa is known worldwide for its leaning tower, the ...
and
Fivizzano and the strongholds of