King Ferdinand I of Aragon, also known as Ferdinand the Catholic, was born in 1452 and became the King of Aragon in 1479. He is best known for his marriage to Queen Isabella I of Castile, which united the two largest kingdoms in Spain. This union laid the foundation for the unification of Spain and the establishment of a powerful Spanish monarchy. Ferdinand played a crucial role in the Spanish Inquisition and the exploration of the New World, supporting Christopher Columbus on his voyages. His reign marked significant political and territorial expansion, contributing to the rise of Spain as a dominant European power during the late 15th century.