The Catholic Monarchs: Unification and State Building

Dynastic Union: Integration of Castile and Aragon

The Battle of Toro secured victory for the Catholic Monarchs against Juana la Beltraneja, who was aided by the King of Portugal. Subsequently, the Treaty of Alcaçovas was signed with Portugal. Upon the death of John II of Aragon, Ferdinand II inherited the kingdom, resulting in a personal political union between Castile and Aragon. Through the Concordia of Segovia, Isabella assumed internal governance of Castile. Following this union, the Kingdom of Granada and Navarre were integrated to achieve the unification of Spain.

Conquest of Granada and Incorporation of Navarre

The incorporation of the Nasrid Kingdom of Granada and the Kingdom of Navarre were pivotal. Relations between Castile and Granada had deteriorated due to continuous border conflicts. Seeking religious unity, the war lasted eleven years, beginning with the capture of Zahara. The Western bloc was conquered first, followed by the Eastern bloc. On January 2, 1492, the surrender of Granada took place at the Alhambra by Boabdil. The aid of the nobility and the Holy Brotherhood was instrumental, and the conquest was facilitated by internal strife within the Nasrid kingdom, despite the difficult terrain and fortifications. Later, following Isabella's death, Ferdinand militarily occupied Pamplona in 1512, completing the incorporation of Navarre.

State Organization: Government Under the Catholic Monarchs

This stage marked the transition from an authoritarian monarchy to the absolute monarchy of the modern age. The foundations of a modern state were established by increasing the monarchy's political power and creating a complex bureaucracy of lawyers and attorneys:

• Royal Council (Council of Castile): Met in specialized committees, including the Inquisition, the Indies, and the Order of Aragon.
• Administration of Justice: Two chancillerías were established in Castile, while the Crown of Aragon established hearings in Aragon, Catalonia, and Valencia.
• Finance and Courts: Reforms were implemented across the courts of Castile and Aragon.

Foreign Policy: Italian and American Expansion

Relations between Castile and France deteriorated, leading to rivalry over Italy. The wars in Italy became a focal point for the French kings and Ferdinand, whose troops were led by Gonzalo Fernández de Córdoba, the "Great Captain." The Kingdom of Naples was secured, alongside Roussillon and Sardinia. The Catholic Monarchs also pursued expansion into the Maghreb to contain Turkish and Berber attacks, though Spanish occupation in Northern Africa remained limited to coastal strongholds.