The Year of Isabella I of Castile – The death of her brother Alfonso

On 5 July 1468, the future Queen Isabella I of Castile mourned the loss of her only full sibling, Alfonso. His death paved the way for her to become the face of the rebellion.

Alfonso was born on 17 November 1453, when Isabella was two years old. Due to male-preference primogeniture, he would precede her in the line of succession to eventually succeed their much older half-brother, King Henry IV of Castile. Alfonso and Isabella lost their father, King John II of Castile, in 1454, upon which Henry became King.

Isabella, Alfonso and their mother moved to Arévalo, where they lived in a two-story house. The town was known for its clean air, and “the plague was rarely known here.”¹ For their mother, these were dark days, and she reportedly shut herself “in a dark room, condemning herself to silence.”² They were soon joined in Arévalo by Isabella of Barcelos, their maternal grandmother. It was Isabella of Barcelos who oversaw their early childhood and education. Alfonso and his sister grew close during this time.

The family spent quite a few quiet years at Arévalo, but as King Henry’s wife Joan came close to giving birth, Henry wanted any potential challengers for the throne kept close by. The ten-year-old Isabella and seven-year-old Alfonso were recalled to court. Isabella later wrote, “Alfonso and I, who were just children at the time, were inhumanely and forcibly torn from our mother’s arms and taken into Queen Juana (Joan)’s power.”³

Isabella and Alfonso said goodbye to their mother and grandmother at the end of 1461 to travel to the court at Segovia. On 28 February 1462, the Queen gave birth to a daughter – Joanna. Isabella acted as godmother for her newborn niece. Joanna was their first child after seven years of marriage and would prove to be the only surviving child. However, it appears that several nobles already doubted Joanna’s legitimacy, not in the least because of jealousy towards Beltrán de la Cueva, who held the King’s favour. It is impossible to tell if Joanna was Beltrán de la Cueva’s daughter, but we know Joan conceived again within the year.

Three months later, Henry had Joanna sworn in as the heiress to the throne, and Isabella and her brother Afonso were the first ones to swear. Isabella later claimed that she knew why some nobles said that they had sworn against their will. She wrote, “It was something she [the Queen] had demanded because she knew the truth about her pregnancy and was taking precautions.”⁴

Nevertheless, the allegations surrounding Joanna’s paternity were the perfect breeding ground for a rebellion. Joanna was just two years old when a manifesto of complaints and grievances was issued against King Henry by several nobles. This led to the Representation of Burgos in 1464, where Henry was forced to recognise Alfonso as the legitimate heir. This was agreed upon with the condition that Alfonso would one day marry Joanna. However, Henry soon reconsidered, and this led to a ceremonial deposition in effigy in 1465, and the 11-year-old Alfonso was crowned as rival King.

Isabella and Alfonso were reunited in 1467 when he triumphantly rode into Segovia as Queen Joan fled. She later wrote, “I stayed in my palace, against the queen’s will, in order to leave her dishonest custody that was bad for my honour and dangerous for my life.”⁵ She made Alfonso’s counsellors sign a document stating that she would not be forced into marriage before agreeing to come with them.

Isabella also asked to return to her mother at Arévalo, and at the end of the year, they celebrated Alfonso’s 14th birthday with the three of them. They stayed there until they were forced to flee due to an outbreak of the plague at the end of June 1468. Alfonso fell ill at Cardeñosa, and for four days, he fought for his life. His death was expected, and Isabella wrote, “And you all know that in the moment that the Lord decided to take his life, succession of the kingdoms and royal lands of Castile and Leon will, as his legitimate heiress and successor, pass to me.”⁶

Alfonso died on 5 July 1468. The battle was now between Joanna and Isabella.

1. Isabella of Castile: Europe’s First Great Queen by Giles Tremlett p.19
2. Isabella of Castile: Europe’s first Great Queen by Giles Tremlett p.19
3. Isabella of Castile: Europe’s First Great Queen by Giles Tremlett p.25
4. Isabella of Castile: Europe’s First Great Queen by Giles Tremlett p.32
5. Isabella of Castile by Giles Tremlett p.39
6. Isabella of Castile by Giles Tremlett p.40