

Juan II died in 1479, and Ferdinand succeeded to the throne in January 1479. Although Aragon provided support for Isabella's cause, Isabella's supporters had extracted concessions, Isabella was acknowledged as the sole heir to the crown of Castile. Isabella called on the aid of Aragon, with her husband, the heir apparent, and his father, Juan II of Aragon providing it. This dispute between rival claimants led to the War of 1475–1479. Joanna sought the aid of her husband (who was also her uncle), Afonso V of Portugal, to claim the throne.

When Henry died in 1474, Isabella asserted her claim to the throne, which was contested by thirteen-year-old Joanna. Henry instead recognised Joanna of Castile, born during his marriage to Joanna of Portugal, but whose paternity was in doubt, since Henry was rumored to be impotent. Isabella's claims to it were not secure, since her marriage to Ferdinand enraged her half-brother Henry IV of Castile and he withdrew his support for her being his heiress presumptive that had been codified in the Treaty of the Bulls of Guisando.

Pope Paul II remained a bitter enemy of Spain and the monarchy for all his life, and the following quote is attributed to him: "May all Spaniards be cursed by God, schismatics and heretics, the seed of Jews and Moors", Some experts point at Carrillo de Acuña, Archbishop of Toledo, and others point at Antonio Veneris. Even though the bull is known to be false, it is uncertain who was the material author of the falsification. Pope Paul II, an Italian pope opposed to Aragon's influence on the Mediterranean and to the rise of monarchies strong enough to challenge the Pope, refused to grant one, so they falsified a papal bull of their own. They were second cousins, so in order to marry they needed a papal dispensation. However, it was a step toward the unification of the lands on the Iberian peninsula, which would eventually become Spain. Both knew that the crown of Castile was "the prize, and that they were both jointly gambling for it". From the start, they had a close relationship and worked well together. They met for the first time in Valladolid in 1469 and married within a week. The title of " Catholic King and Queen" was officially bestowed on Ferdinand and Isabella by Pope Alexander VI in 1494, in recognition of their defence of the Catholic faith within their realms.įirst Royal Standard of the Catholic Monarchs (1475–1492)Īt the time of their marriage on October 19, 1469, Isabella was eighteen years old and the heiress presumptive to the Crown of Castile, while Ferdinand was seventeen and heir apparent to the Crown of Aragon. The court of Ferdinand and Isabella was constantly on the move, in order to bolster local support for the crown from local feudal lords. Spain was formed as a dynastic union of two crowns rather than a unitary state, as Castile and Aragon remained separate kingdoms until the Nueva Planta decrees of 1707–1716. It is generally accepted by most scholars that the unification of Spain can essentially be traced back to the marriage of Ferdinand and Isabella. They married on October 19, 1469, in the city of Valladolid Isabella was eighteen years old and Ferdinand a year younger. They were both from the House of Trastámara and were second cousins, being both descended from John I of Castile to remove the obstacle that this consanguinity would otherwise have posed to their marriage under canon law, they were given a papal dispensation by Sixtus IV. The Catholic Monarchs were Queen Isabella I of Castile and King Ferdinand II of Aragon, whose marriage and joint rule marked the de facto unification of Spain.
