Ferdinand III of Castile was a significant medieval king who ruled from 1217 to 1252. He was born in 1199 and became known for his efforts to expand the territories of the Kingdom of Castile and Leon. His reign is marked by the successful conquest of Seville and other important cities during the Reconquista, a campaign to reclaim land from the Moors. Ferdinand III was also recognized for his commitment to justice and the promotion of Christian values. He was canonized as a saint by the Catholic Church in 1671, reflecting his lasting impact on Spanish history and culture. His legacy continues to be celebrated in Spain today.