Isabella I of Castile reigned from 1474 until her death in 1504 alongside her husband, Ferdinand II, King of Aragon. Together, they were known as the Catholic Monarchs.
When Isabella’s step-brother, King Henry IV, died, Castile entered into a war of succession between Isabelle and Joanna la Beltraneja, reputed to be the daughter of Henry IV.
Following the Battle of Toro, the throne was secured for Isabella after signing the Treaty of Alcáçovas.
The reign of Isabella the Catholic led the transition from the Middle Ages to the Modern Age.
Her marriage brought the unification of the crowns of Castile and Aragon as well as the creation of a professional army under the single control of the crown. As such, Isabella and Ferdinand were the first monarchs to be called “monarchs of Spain”.
Another of Isabella the Catholic’s significant successes was the completion of the “Reconquista” which had begun seven centuries beforehand with the Christian monarchs fighting against the Muslim invasion of the Iberian peninsula.
In 1492, Nasrid ruler Boabdil handed over the city of Granada to the Catholic Monarchs. During the siege of Granada, Queen Isabella personally intervened by mobilising resources and organising field hospitals with great effectiveness.
Once Granada had been conquered, Isabella the Catholic believed in Christopher Columbus’ exploration plans and sponsored the passage that would result in the discovery of America on the 12th of October 1492 – a milestone journey, not just in the history of Spain, but in the history of humankind.
Through the Capitulations of Santa Fe, the Catholic Queen appointed Columbus as admiral, governor and viceroy of the territories to be discovered.
An administration was created in Seville through the Casa de Contratación to monopolise all trade and, most importantly, the bases of the Laws of the Indies were established.
Following the discovery of the new world, Isabella the Catholic was the first person to show concern for the rights of the Indians. She ordered the indigenous peoples to be treated as subjects of her kingdom and therefore as free men, banning slavery, and she determined that they would continue to own their land.
During her reign, Isabella brought about the religious unification around Catholicism. With the bull issued by Pope Sixtus IV, the Spanish Inquisition was created to defend the orthodoxy of Catholicism.
Once Granada had been conquered, the Catholic Monarchs decreed forced conversion to Christianity for Jews and, years later, for Muslims, too, and expulsion from the kingdom for those who would not accept this.
The queen’s defence of Catholicism led Pope Alexander VI to award Isabella and Ferdinand the title of Catholic Monarchs.
Finally, among Isabella the Catholic’s successes, we must not forget her search throughout Europe to find marriage alliances for her children.
To strengthen relations with Portugal, she married Isabella, her first-born, to Alfonso, King of Portugal. She married her daughter Catherine to Henry VIII of England. Her other two children, John and Joanna, married the daughter and son of Emperor Maximilian I, Margaret and Philip the Handsome.
As a result of the state marriages arranged by Queen Isabella, Spain became a great European power.
The Spanish monarchy also incorporated the Kingdom of Naples into the crown thanks to the troops led by Gonzalo Fernández de Córdoba, known as the Great Captain.
Her personality, marked by the renaissance culture, inspired an architectural style called the Isabelline Gothic, with buildings such as San Juan de los reyes in Toledo, the Cartuja de Miraflores in Burgos, the Los Jerónimos church in Madrid and the Royal Chapel of Granada, where her remains lie.
