Isabella of Castile: The Marriage Her Brother Did Not Approve

She was eighteen, and the husband she chose had promised not to take her away. Her brother was the king. He had other plans for her.

On 19 October 1469, Isabella of Castile married Ferdinand of Aragon in the house of Juan de Vivero at Valladolid. He was seventeen, already King of Sicily and heir to his father's Aragonese crown. She was the recognised heir to Castile, where her half-brother Henry IV still ruled. Neither yet possessed the inheritance that would make their marriage so powerful. Both had relatives and supporters with a considerable interest in what happened next.

Isabella was a daughter of King John II of Castile, but royal birth had placed other people ahead of her. Henry was her elder half-brother; her younger brother Alfonso also took precedence in the succession. During Henry's reign, rebellious nobles had set Alfonso up as a rival king. When Alfonso died in 1468, they offered to support Isabella in his place. She declined to take her living brother's crown and negotiated to inherit it instead.

The settlement recognised her as Henry's successor, displacing his six-year-old daughter Juana. That child's legitimacy had become a weapon in the struggle between the king and his opponents. Isabella's position rested on an agreement with a man who had a daughter of his own, and on the support of nobles who had already tried replacing him once. Recognition could be secured. Keeping it was another matter.

Marriage belonged inside that bargain. Henry was to propose a husband whom Isabella would accept. She was not to be forced into a match against her will, but neither had he surrendered his interest in choosing it. There was enough room in the arrangement for both brother and sister to believe that their consent mattered. The difficulty came when they consented to different things.

Henry favoured Afonso V of Portugal, a widowed king nearly twenty years older than Isabella. A Portuguese marriage offered an alliance between kings and an established crown. It also meant sending the woman recognised as Castile's heir into another king's household. Isabella refused. To the two men closest to her household, Gonzalo Chacón and Gutierre de Cárdenas, she put it plainly: she would marry Ferdinand, and no other.

He brought powerful connections of his own. His father, John II of Aragon, had reason to welcome Castilian support, and Isabella's supporters had reason to welcome an Aragonese ally. Isabella had secured a part in deciding which alliance her marriage would serve, and what it would require of her husband.

And there were conditions.

In the marriage agreement negotiated at Cervera earlier that year, Ferdinand undertook to live with Isabella in Castile. He was not to take her out of its kingdoms without her consent. The husband was to come to her. For a princess whose marriage concerned the succession to Castile, where she lived was a matter of government as well as home.

The agreement went further. If they had children, sons or daughters, Ferdinand promised not to separate them from their mother or take them out of those kingdoms. Before there was a nursery, there was a provision about who could remove its children.

Their documents were to bear both signatures. Ferdinand could not simply give away Crown towns or fortresses without Isabella's consent. These were practical limits on what marriage would allow him to do. A husband could be an ally without being given an unrestricted hand over the inheritance his wife expected to receive.

Getting him to her took a disguise. That October Ferdinand crossed into Castile secretly, travelling as a servant in an embassy his father had sent, and reached Dueñas before going on to Valladolid.

The wedding made them husband and wife. It did not settle their position in Castile.

At Valladolid, Alfonso Carrillo, Archbishop of Toledo and a supporter of the match, married them. Henry had not given his consent. The brother whose recognition Isabella needed as heir had been bypassed in the choice of the man who would stand beside her. Her marriage strengthened one alliance while giving her opponents a new objection to her claim.

She would become Queen of Castile in 1474, and Ferdinand would inherit Aragon in 1479. The power they eventually held together was also used to persecute. In 1492 they ordered the Jews of their kingdoms to convert or leave.

In October 1469, however, acceptance still had to be sought. The newly married couple sent messages asking nobles to support their marriage and approach Henry on their behalf. They assured the king of their obedience. On 29 October they notified Murcia of the marriage and asked the city to declare its support.

The following day, Isabella appealed to the Countess of Plasencia to intervene with Henry. She was eighteen, with the husband she had chosen and the terms of their marriage agreed. Eleven days after the wedding, she was asking another woman to help persuade her brother to approve it.