Cosimo I de' Medici (12 June 1519 – 21 April 1574) was the second and last
duke of Florence from 1537 until 1569, when he became the first
grand duke of Tuscany
Grand may refer to:
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* Grand, Oklahoma, USA
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, a title he held until his death. Cosimo I succeeded his cousin to the duchy. He built the
Uffizi
The Uffizi Gallery ( ; , ) is a prominent art museum adjacent to the Piazza della Signoria in the Historic Centre of Florence in the region of Tuscany, Italy. One of the most important Italian museums and the most visited, it is also one of th ...
(office) to organize his administration, and conquered
Siena
Siena ( , ; traditionally spelled Sienna in English; ) is a city in Tuscany, in central Italy, and the capital of the province of Siena. It is the twelfth most populated city in the region by number of inhabitants, with a population of 52,991 ...
to consolidate Florence's rule in Tuscany. He expanded the
Pitti Palace and most of the
Boboli Gardens were also laid out during his reign.
Life
Rise to power
Cosimo was born in
Florence
Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025.
Florence ...
on 12 June 1519, the son of the famous
condottiere Ludovico de' Medici (known as
Giovanni delle Bande Nere) and his wife
Maria Salviati, herself a granddaughter of
Lorenzo the Magnificent. He was the grandson of
Caterina Sforza, the Countess of Forlì and Lady of
Imola. Cosimo became Duke of Florence in 1537 at age 17, after the former Duke of Florence,
Alessandro de' Medici, 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. 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 or direct descendant, in legal usage, is a blood relative in a person's direct line of descent – the children, grandchildren, great-grandchildren, etc. In a legal procedure sense, lineal descent refers to the acquisition of estate ...
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) 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 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 located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
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 ( ) or Agnolo Bronzino, was an Italians, Italian Mannerism, Mannerist painter from Florence. His sobriquet, ''Bronzino'', may refer to his relatively dark skin or r ...
.
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
() is a w-shaped Town Square, square in front of the in Florence, Central Italy. It was named after the Palazzo della Signoria, also called . It is the main point of the origin and history of the Florentine Republic and still maintains its reput ...
or in the
Bargello.
Filippo Strozzi's body was found with a bloody sword next to it and a note quoting
Virgil
Publius Vergilius Maro (; 15 October 70 BC21 September 19 BC), usually called Virgil or Vergil ( ) in English, was an ancient Rome, ancient Roman poet of the Augustan literature (ancient Rome), Augustan period. He composed three of the most fa ...
, but many believe that his suicide was faked.
Rule of Tuscany

In 1537, Cosimo sent
Bernardo Antonio de' Medici to Holy Roman Emperor
Charles V 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. With this move, Cosimo firmly restored the power of the
Medici, who thereafter ruled
Florence
Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025.
Florence ...
until the death of the last of the Medici rulers,
Gian Gastone de' Medici, 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 ( , ; traditionally spelled Sienna in English; ) is a city in Tuscany, in central Italy, and the capital of the province of Siena. It is the twelfth most populated city in the region by number of inhabitants, with a population of 52,991 ...
. With the support of Charles V, he defeated the Sienese at the
Battle of Marciano 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 40,000 to 8,000 people. In 1559,
Montalcino, the last redoubt of Sienese independence, was annexed to Cosimo's territories. In 1569,
Pope Pius 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 disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...
, 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. 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 ( ; ; , formerly ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 islands that are separated by expanses of open water and by canals; portions of the city are li ...
. 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 ( , ; ) 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 of Above mean sea level, above sea level. As of 2 ...
,
Sansepolcro, the new walls of
Pisa
Pisa ( ; ) is a city and ''comune'' (municipality) 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 the Leaning Tow ...
and
Fivizzano and the strongholds of
Portoferraio on the island of
Elba and
Terra del Sole.
He laid heavy tax burdens on his subjects. Despite his economic difficulties, Cosimo I was a lavish patron of the arts and also developed the Florentine navy, which eventually took part in the
Battle of Lepanto
The Battle of Lepanto was a naval warfare, naval engagement that took place on 7 October 1571 when a fleet of the Holy League (1571), Holy League, a coalition of Catholic states arranged by Pope Pius V, inflicted a major defeat on the fleet of t ...
, and which he entrusted to his new creation, the
Knights of St. Stephen.
Patronage of the arts

Cosimo is perhaps best known today for the creation of the
Uffizi
The Uffizi Gallery ( ; , ) is a prominent art museum adjacent to the Piazza della Signoria in the Historic Centre of Florence in the region of Tuscany, Italy. One of the most important Italian museums and the most visited, it is also one of th ...
("offices"). Originally intended as a means of consolidating his administrative control of the various committees, agencies, and guilds established in Florence's Republican past, it now houses one of the world's most important collections of art, much of it commissioned and/or owned by various members of the Medici family.
His gardens at
Villa di Castello, designed by
Niccolò Tribolo when Cosimo was only seventeen years old, were designed to announce a new golden age for Florence and to demonstrate the magnificence and virtues of the Medici. They were decorated with fountains, a
labyrinth
In Greek mythology, the Labyrinth () is an elaborate, confusing structure designed and built by the legendary artificer Daedalus for King Minos of Crete at Knossos. Its function was to hold the Minotaur, the monster eventually killed by the h ...
, a
grotto and ingenious ornamental water features, and were a prototype for the
Italian Renaissance garden. They had a profound influence on later Italian and French gardens through the eighteenth century.
[Isabella Ballerini (2011), ''The Medici Villas'', Giunti Publishers, Florence (), pp. 30-41]
Cosimo also finished the
Pitti Palace as a home for the Medici and created the magnificent
Boboli Gardens behind the Pitti. As his more prominent ancestors had been, he was also an important patron of the arts, supporting, among others,
Giorgio Vasari
Giorgio Vasari (30 July 1511 – 27 June 1574) was an Italian Renaissance painter, architect, art historian, and biographer who is best known for his work ''Lives of the Most Excellent Painters, Sculptors, and Architects'', considered the ideol ...
,
Benvenuto Cellini,
Pontormo,
Bronzino
Agnolo di Cosimo (; 17 November 150323 November 1572), usually known as Bronzino ( ) or Agnolo Bronzino, was an Italians, Italian Mannerism, Mannerist painter from Florence. His sobriquet, ''Bronzino'', may refer to his relatively dark skin or r ...
, the architect
Baldassarre Lanci, and the historians
Scipione Ammirato
Scipione Ammirato (; 7 October 153111 January 1601) was an Italian author, Philosophy, philosopher and historian who lived during the Renaissance. He is regarded as an important figure in the history of political thought.
Ammirato's best-known w ...
and
Benedetto Varchi.
A large bronze equestrian statue of Cosimo I by
Giambologna, erected in 1598, still stands today in the
Piazza della Signoria
() is a w-shaped Town Square, square in front of the in Florence, Central Italy. It was named after the Palazzo della Signoria, also called . It is the main point of the origin and history of the Florentine Republic and still maintains its reput ...
, the main square of Florence.
Cosimo was also an enthusiast of
alchemy
Alchemy (from the Arabic word , ) is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practised in China, India, the Muslim world, and Europe. In its Western form, alchemy is first ...
, a passion he inherited from his grandmother
Caterina Sforza.
Marriage and family

In 1539, Cosimo married the Spanish noblewoman
Eleanor of Toledo (1522 – 1562), the daughter of
Don Pedro Álvarez de Toledo, the Spanish
viceroy
A viceroy () is an official who reigns over a polity in the name of and as the representative of the monarch of the territory.
The term derives from the Latin prefix ''vice-'', meaning "in the place of" and the Anglo-Norman ''roy'' (Old Frenc ...
of
Naples
Naples ( ; ; ) is the Regions of Italy, regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its Metropolitan City of N ...
. The couple had a long and peaceful married life. Surprisingly for the era, Cosimo was faithful to his wife throughout their married life. The example of a traditional couple served to strengthen his various reforms and separate their association with the former Duke. Eleanor was a political adviser to her husband and often ruled Florence in his absence. She provided the Medici with the
Pitti Palace and was a patron of the new
Jesuit
The Society of Jesus (; abbreviation: S.J. or SJ), also known as the Jesuit Order or the Jesuits ( ; ), is a religious order (Catholic), religious order of clerics regular of pontifical right for men in the Catholic Church headquartered in Rom ...
order. The Duchess died with her sons Giovanni and Garzia in 1562, when she was only forty; all three of them were struck down by
malaria
Malaria is a Mosquito-borne disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...
while traveling to
Pisa
Pisa ( ; ) is a city and ''comune'' (municipality) 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 the Leaning Tow ...
.
Cosimo and Eleanor had:
*
Maria (3 April 1540 – 19 November 1557), engaged to
Alfonso II d'Este, but died before the marriage
*
Francesco
Francesco, the Italian language, Italian (and original) version of the personal name "Francis (given name), Francis", is one of the List of most popular given names, most common given name among males in Italy. Notable persons with that name inclu ...
(25 March 1541 – 19 October 1587), Cosimo's successor as Grand Duke of Tuscany
*
Isabella (31 August 1542 – 16 July 1576), murdered by her husband
Paolo Giordano I Orsini because of infidelity
*
Giovanni (28 September 1543 – 20 November 1562), who became
Bishop of Pisa and a cardinal
*
Lucrezia (7 June 1545 – 21 April 1561), who married
Alfonso II d'Este,
Duke of Ferrara
This is a list of rulers of the estates owned by the House of Este, Este family, which main line of Marquesses (''Marchesi d'Este'') rose in 1039 with Albert Azzo II, Margrave of Milan. The name "Este" is related to the city where the family came ...
and
Modena
Modena (, ; ; ; ; ) is a city and ''comune'' (municipality) on the south side of the Po Valley, in the Province of Modena, in the Emilia-Romagna region of northern Italy. It has 184,739 inhabitants as of 2025.
A town, and seat of an archbis ...
, in 1560
*Pietro (Pedricco) (10 August 1546 – 10 June 1547), who died in infancy
*
Garzia (5 July 1547 – 12 December 1562), who died of
malaria
Malaria is a Mosquito-borne disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...
at age 15
*Antonio (1 July 1548 – July 1548), who died in infancy
*
Ferdinando (30 July 1549 – 17 February 1609), Francesco's successor as Grand Duke of Tuscany
*Anna (19 March 1553 – 6 August 1553), who died in infancy
*
Pietro (3 June 1554 – 25 April 1604), who murdered his wife
Eleonora di Garzia di Toledo
Before his first marriage, Cosimo fathered an illegitimate daughter with an unknown woman:
*
Bia de' Medici (ca. 1536 – March 1, 1542)
After Eleanor's death in 1562, Cosimo fathered two children with his mistress
Eleonora degli Albizzi:
*an unnamed daughter (born and died 1566) who died before baptism''
*
Giovanni (1567 – 1621), later legitimized by his father
In 1570, Cosimo married
Camilla Martelli (died 1590) and fathered one child with her:
*
Virginia
Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...
(29 May 1568 – 15 January 1615), who married
Cesare d'Este,
Duke of Modena
References
Sources
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Further reading
*
*
* Henk Th. Van Veen, ''Cosimo I de' Medici and his Self-Representation in Florentine Art and Culture'' (Cambridge, CUP, 2006).
* Gáldy, Andrea M. ''Cosimo I de'Medici as collector: antiquities and archaeology in sixteenth-century Florence'' (Newcastle: Cambridge Scholars Publishing, 2009).
External links
*
Tales From The Crypt: Reports On The Exhumation Of The Medici Tombs In Italy
, -
{{DEFAULTSORT:Cosimo 1
1519 births
1574 deaths
16th-century Italian nobility
16th-century monarchs in Europe
16th-century grand dukes of Tuscany
Cosimo 1
Cosimo 1
Tuscan nobility
Italian patrons of the arts
Knights of the Golden Fleece
1560s in the Grand Duchy of Tuscany
1570s in the Grand Duchy of Tuscany
16th century in the Grand Duchy of Tuscany
Italian Roman Catholics
Italian art patrons