linguistic:translation, information:classification
Failed betrothals

The question of Isabella's marriage was not a new one. She had, at the age of six, a betrothal to Ferdinand, the younger son of John II of Navarre (whose family was a cadet branch of the House of Trastámara). At that time, the two kings, Henry and John, were eager to show their mutual love and confidence and they believed that this alliance would make their eternal friendship obvious to the world. This arrangement, however, did not last long.

Ferdinand's uncle Alfonso V of Aragon died in 1458. All of Alfonso's Spanish territories, as well as the islands of Sicily and Sardinia, were left to his brother John II. John now had a stronger position than ever before and no longer needed the security of Henry's friendship. Henry was now in need of a new alliance. He saw the chance for this much-needed new friendship in Charles of Viana, John's elder son. Charles was constantly at odds with his father, and because of this, he secretly entered into an alliance with Henry IV of Castile. A major part of the alliance was that a marriage was to be arranged between Charles and Isabella. When John II learned of this arranged marriage, he was outraged. Isabella had been intended for his favorite younger son, Ferdinand, and in his eyes, this alliance was still valid. John II had his son Charles thrown in prison on charges of plotting against his father's life. Charles died in 1461.

In 1465, an attempt was made to marry Isabella to Afonso V of Portugal, Henry's brother-in-law. Through the medium of the queen and Count of Ledesma, a Portuguese alliance was made. Isabella, however, was wary of the marriage and refused to consent.

A civil war broke out in Castile over King Henry's inability to act as sovereign. Henry now needed a quick way to please the rebels of the kingdom. As part of an agreement to restore peace, Isabella was then to be betrothed to Pedro Girón Acuña Pacheco, Master of the Order of Calatrava and brother to the king's favorite, Juan Pacheco. In return, Don Pedro would pay into the royal treasury an enormous sum of money. Seeing no alternative, Henry agreed to the marriage. Isabella was aghast and prayed to God that the marriage would not come to pass. Her prayers were answered when Don Pedro suddenly fell ill and died while on his way to meet his fiancée.

When Henry had recognized Isabella as his heir-presumptive on 19 September 1468, he had also promised that his half-sister should not be compelled to marry against her will, while she in return had agreed to obtain his consent. It seemed that the years of failed attempts at political marriages were finally over. There was talk of a marriage to Edward IV of England or to one of his brothers, probably Richard, Duke of Gloucester, but this alliance was never seriously considered. Once again in 1468, a marriage proposal arrived from Afonso V of Portugal. Going against his promises made in September 1468, Henry tried to make the marriage a reality. If Isabella married Afonso, Henry's daughter Joanna would marry Afonso's son John II and thus, after the death of the old king, John and Joanna could inherit Portugal and Castile. Isabella refused and made a secret promise to marry her cousin and very first betrothed, Ferdinand of Aragon.

After this failed attempt, Henry once again went against his promises and tried to marry Isabella to Louis XI 's brother Charles, Duke of Berry. In Henry's eyes, this alliance would cement the friendship of Castile and France as well as remove Isabella from Castilian affairs. However, Isabella once again refused the proposal. Meanwhile, John II of Aragon negotiated in secret with Isabella a wedding to his son Ferdinand. After her marriage to Ferdinand, several anonymous journal entries claim the queen was unfaithful and plotted against the king.