by Susan Flantzer
© Unofficial Royalty 2022

Isabella I, Queen of Castile and León was born on April 22, 1451, at the Royal Palace (later the Monastery of Our Lady of Grace) in the town of Madrigal de las Altas Torres, then in the Kingdom of Castile and León, now in the Kingdom of Spain. Isabella (Isabel in Spanish) was the elder of the two children of Juan II, King of Castile and León and his second wife Isabel of Portugal. Isabella’s paternal grandparents were Enrique III, King of Castile and Catherine of Lancaster. Catherine of Lancaster was the daughter of John of Gaunt, 1st Duke of Lancaster, a son of King Edward III of England. Isabella had golden-red hair from her father’s descent from the English House of Plantagenet. Isabella’s maternal grandparents were Infante Juan of Portugal and Isabel de Barcelos of the House of Braganza.

The marriage of Queen Isabella I of Castile and León (reigned 1474 – 1504) and King Ferdinand II (Fernando in Spanish) of Aragon (reigned 1479 – 1516) led to the political unification of the Kingdom of Aragon and the Kingdom of Castile and León into the Kingdom of Spain under their grandson King Charles I (Carlos in Spanish), King of Spain who later also became Charles V, Holy Roman Empire. Isabella and Ferdinand will be used in this article because that is how they are generally known, especially in the United States.

Isabella had one brother who died when he was fourteen years old:

• Alfonso of Castile, Prince of Asturias (1453 – 1468)

Isabella had four half-siblings from her father’s first marriage to his first cousin Maria of Aragon:

• Catalina of Castile, Princess of Asturias (1422 – 1424), died in childhood, heiress presumptive from her birth until her death
• Leonor of Castile, Princess of Asturias (1423 – 1425), died in childhood, heiress presumptive from the death of Catalina until the birth of her brother Enrique
• King Enrique IV of Castile and León (1425 – 1474), married (1) Blanche of Navarre, no children, marriage annulled (2) Joana of Portugal, had one daughter whose paternity is in doubt, divorced
• Infanta Maria of Castile (1428 – 1429), died in infancy

At the time of her birth, Isabella was second in line to the throne of Castile and León after her 26-year-old half-brother Enrique. Enrique’s first marriage was childless. Two years after her birth, Isabella’s brother Alfonso was born but he died when he was fourteen. Isabella and her half-brother Enrique were the only children of their father Juan II, King of Castile and León to survive childhood. Enrique’s second wife Joana of Portugal did give birth to a daughter but her paternity is in doubt. Enrique had no other children and was rumored to be impotent. His wife’s daughter was popularly called Joanna la Beltraneja, referring to Beltrán de la Cueva, 1st Duke of Alburquerque, who was suspected of her father.

When Juan II, King of Castile and León died in 1454, his son succeeded him as Enrique IV, King of Castile and León. Isabella was only three years old when her father died. Although her father arranged for Isabella, her brother Alfonso, and their mother to be financially secure, Enrique IV did not always follow his father’s wishes. Initially, after her father’s death, Isabella, her brother, and their mother lived at the Castle of Arévalo, where Isabella, under the guidance of her mother, developed a deep reverence for the Catholic religion. In 1462, eleven-year-old Isabella and her brother Alfonso were summoned to court at the Alcázar of Segovia under the direct supervision of their half-brother Enrique IV. Alfonso was placed in the care of a tutor while Isabella became part of the Queen’s household and received a well-rounded education.

Enrique IV made several unsuccessful attempts to marry Isabella to grooms of his choice. His half-sister was resistant and a few of the intended grooms died. When Isabella reached the age of eighteen, she decided she wanted to choose her own husband. She chose Ferdinand of Aragon, the heir apparent of Juan II, King of Aragon and his second wife Juana Enriquez, 5th Lady of Casarrubios del Monte. Without her half-brother’s knowledge, Isabella contacted Ferdinand through Abraham Seneor, who would become her longtime advisor, and marriage arrangements were made.

Fearing that Enrique IV would disrupt the marriage plans, Isabella made the excuse of wanting to visit the burial place of her brother Alfonso in Ávila. She then traveled to Valladolid. Ferdinand disguised himself as a muleteer for some merchants and secretly traveled with a few companions to Valladolid. On October 19, 1469, Isabella and Ferdinand were married at the Palacio de los Vivero in Valladolid.

Through the marriages of their five children, Isabella and Ferdinand’s grandchildren were the monarchs or consorts of Bohemia and Hungary; Denmark, Sweden, and Norway; England; France, the Holy Roman Empire; Portugal; and Spain.

Isabella and Ferdinand had five children:

• Isabella of Aragon, Princess of Asturias from 1497–1498 (1470 – 1498), married (1) Prince Afonso of Portugal, no children (2) Prince Manuel, the future King Manuel I of Portugal, had one son Miguel da Paz, Crown Prince of both Portugal and Spain who died before his second birthday; Isabella died giving birth to Miguel
• Juan of Aragon, Prince of Asturias (1478 – 1497), married Margaret of Austria, no children
• Juana I, Queen of Castile, Queen of Aragon (1479 – 1555), married Philip of Austria (the Handsome), son of the Holy Roman Emperor Maximilian I and Mary, Duchess of Burgundy; had six children, all of whom were kings or queens consorts: Eleanor of Austria, Queen of Portugal and Queen of France; Holy Roman Emperor Charles V/King Carlos I of Spain; Isabella of Austria, Queen of Denmark, Norway, and Sweden; Mary, Queen of Hungary and Bohemia; Catherine of Austria, Queen of Portugal
• Maria of Aragon (1482 – 1517), married King Manuel I of Portugal, the widower of her elder sister Isabella; had ten children including King João III of Portugal and Cardinal-King Henrique I of Portugal
• Catalina (Catherine) of Aragon (1485 – 1536), married (1) Arthur, Prince of Wales, no children (2)  King Henry VIII of England (Arthur’s younger brother), had one surviving child Queen Mary I of England

When Enrique IV, King of Castile and León died in 1474, his half-sister succeeded him as Isabella I, Queen of Castile and León. Joanna la Beltraneja, the daughter of Enrique IV’s second wife, claimed the throne of Castile and León and was supported by some of the Castilian nobility and by Portugal, her mother’s birthplace. However, the Battle of Toro during the War of the Castilian Succession secured the throne of Castile and León for Isabella. According to the prenuptial agreement signed at the time of Isabella’s marriage to the future Ferdinand II, King of Aragon, the couple would share their power. Ferdinand became jure uxoris (by the right of his wife) King of Castile when Isabella succeeded her brother. When Ferdinand succeeded his father as King of Aragon in 1479, the Crown of Castile and the various territories of the Crown of Aragon were united in a personal union.

The marriage of Isabella and Ferdinand created the de facto unification of Spain. They carefully considered the marriages of their children. Their only son and heir Juan, Prince of Asturias married a Habsburg princess, Margaret of Austria, establishing the connection to the Habsburgs. Their eldest child Isabella married King Manuel I of Portugal and another daughter Juana married a Habsburg prince, Philip of Austria (the Handsome), brother of Margaret of Austria. However, Isabella and Ferdinand’s plans for their two eldest children did not work out. Their only son Juan, Prince of Asturias, died shortly after his marriage. Their daughter Isabella died during the birth of her only child Miguel da Paz, who died shortly before his second birthday. Isabella and Ferdinand’s crowns ultimately passed to their third child Juana and their son-in-law Philip of Austria from the House of Habsburg. Juana and Philip’s son Carlos (also known as Charles) became the first King of a united Spain, and also Holy Roman Emperor, Archduke of Austria, and Lord of the Netherlands.

Isabella and Ferdinand made successful dynastic matches for their two youngest daughters. The death of their eldest child Isabella necessitated her husband King Manuel I of Portugal to remarry, and Ferdinand and Isabella’s third daughter Maria became the second of his three wives. Maria gave birth to ten children including two Kings of Portugal. Ferdinand and Isabella’s youngest child Catherine (Catalina in Spanish) of Aragon, married Arthur, Prince of Wales, the eldest son and heir of King Henry VII of England. Arthur’s early death resulted in Catherine becoming the first of the six wives of his younger brother King Henry VIII of England. Although King Henry VIII was dissatisfied that his marriage to Catherine had produced no surviving sons, their only surviving child Mary was a reigning Queen of England.

Isabella and Ferdinand’s support of Christopher Columbus in his search for the West Indies would result in the conquest of the discovered lands and the creation of the Spanish Empire. In 1478, Isabella and Ferdinand established the Spanish Inquisition to maintain the Roman Catholic religion in their kingdoms. The Spanish Inquisition was originally intended to identify heretics among those who had converted from Judaism and Islam to Catholicism. In 1492, Isabella and Ferdinand conquered the Islamic Nasrid Kingdom of Granada, in today’s southern Spain, and issued the Alhambra Decree which ordered the mass expulsion of Jews from Spain. Because they defended the Roman Catholic Church in Castile and León and Aragon, Isabella and Ferdinand were given the Latin title Rex Catholicissimus (Most Catholic King or Most Catholic Majesty) by Pope Alexander VI in 1494. Thereafter, they used the Spanish title Los Reyes Católicos, generally translated as “The Catholics Monarchs”. It is still a title maintained by the Spanish monarchy but neither King Juan Carlos I (reigned 1975 – 2014, abdicated in favor of his son), nor his son Felipe VI, the current King of Spain, have made use of the title, but they have not renounced it either.

Isabella’s health had been in decline since the death of her only son Juan, Prince of Asturias in 1497. In the fall of 1504, she became quite ill and officially withdrew from government affairs. On November 26, 1504, Isabella died at the age of 53 at the Royal Palace in Medina del Campo, Valladolid, Kingdom of Castile, now in Spain.

In her will, Isabella requested a simple burial at the Monastery of San Francisco in the Alhambra royal complex in Granada. She also further stated that she “wanted and commanded” that if Ferdinand “chooses to buried in any church or monastery of any other part or place of my kingdoms, that my body be moved there and buried together.” Isabella was first buried, in accordance with her wishes, at the Monastery of San Francisco in the Alhambra royal complex in Granada. Her remains were later transferred to the Royal Chapel of Granada which was built after her death.

Two years after Isabella’s death, Ferdinand married Germaine of Foix, the granddaughter of his half-sister Queen Eleanor of Navarre and the niece of King Louis XII of France. Ferdinand and Germaine had one son Juan, Prince of Girona, who died shortly after his birth. Had he survived, the crown of Aragon would have been separated from the crown of Castile. Ferdinand survived Isabella by twelve years, dying at the age of 63 on January 23, 1516, and was buried next to his first wife Isabella at the Royal Chapel of Granada as Isabella requested.

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Works Cited

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