Ferdinand I of Aragon was a significant historical figure who ruled as King of Aragon from 1412 until his death in 1416. He was born in 1380 and became known for his efforts to unify the various kingdoms of Spain. His reign marked the beginning of a more centralized Spanish monarchy. Ferdinand was also a member of the House of Trastámara and played a crucial role in the political landscape of medieval Iberia. His marriage to Isabella I of Castile in 1469 later united the crowns of Aragon and Castile, paving the way for the eventual unification of Spain.