How were the kingdoms of Casitlle and Aragon united and when?

The kingdoms of Castile and Aragon were united through the marriage of Isabella I of Castile and Ferdinand II of Aragon in 1469. This dynastic union laid the foundation for the eventual political unification of Spain. Although Castile and Aragon remained distinct entities for some time, their combined rule significantly strengthened the two kingdoms, culminating in the formal unification of Spain in 1492 with the completion of the Reconquista.