The marriage of Ferdinand II of Aragon and Isabella I of Castile was a significant alliance that marked the beginning of Spain as a unified kingdom. Celebrated in Valladolid, this union linked two prominent dynasties and formed a foundation for political and territorial unification in the Iberian Peninsula. At the time, both kingdoms were influential yet separate, often competing for resources and influence. By marrying, Ferdinand and Isabella not only secured their own thrones but also aimed to consolidate their realms against the common threats they faced from neighboring kingdoms and the Reconquista efforts against the Muslim kingdoms in Granada.

The wedding took place in an atmosphere filled with political tension and expectation. The couple's marriage was seen as a turning point, promising greater stability and cooperation between Aragon and Castile. In the following years, they would work together to unify their forces, leading to the conquest of Granada in 1492, and thus concluding the Reconquista. This victory not only shaped the religious landscape of Spain but also marked the era of Spanish exploration and colonization of the New World.

Through their reign, Ferdinand and Isabella also laid the groundwork for modern statehood in Spain, promoting reforms in governance and thereby elevating Spain’s position in Europe. Their lineage continued to influence Spanish politics long after their reign, further entwining their realms under a single crown and initiating a period of great cultural and economic growth often referred to as the Golden Age of Spain.