In 1217, Ferdinand III became king of Castile after his mother, Berenguela, passed the crown to him. His early rule focused on stabilizing the kingdom so it could sustain major campaigns further south.
In December 1230, Ferdinand secured the crown of León through the Treaty of Benavente, negotiated with his half-sisters and their supporters. This created a stronger, permanently united realm, giving Ferdinand more manpower and revenue for large-scale offensives in al-Andalus.
Castilian forces moved against Córdoba in early 1236, exploiting internal weakness and divisions in the city’s defenses. Capturing Córdoba mattered strategically and symbolically because it was a major urban center of Islamic Iberia and a key node on routes into the Guadalquivir valley.
On 29 June 1236, Córdoba surrendered to Ferdinand III, ending centuries of Muslim rule in the city. The conquest opened the way for further Castilian advances into southern Iberia and reshaped the balance of power in the region.
After the conquest, the city’s main mosque was consecrated for Christian worship and became the cathedral of Córdoba. This signaled a new religious and political order and helped anchor long-term Castilian control through church institutions.
By 1245, Ferdinand pushed east and targeted Jaén, a fortress city that helped guard routes between the Guadalquivir region and Granada. Taking Jaén would limit Muslim counterattacks and put pressure on the emerging Nasrid power in Granada.
By early 1246, the defense of Jaén collapsed, and the city was handed over after negotiations tied to the Treaty (Pact) of Jaén. The agreement helped establish the Emirate of Granada as a tributary and politically dependent neighbor, reducing the chance of a unified Muslim front against Castile.
In July 1247, Ferdinand’s forces began a long siege of Seville, then a major city of Islamic southern Iberia. Seville’s location on the Guadalquivir River made it economically important and hard to conquer without cutting supplies by land and water.
During the siege, a Castilian fleet under Ramón de Bonifaz attacked the river barrier that protected Seville’s supply line. Breaking this defense helped isolate the city more completely and accelerated the outcome of the siege.
On 23 November 1248, Seville surrendered to Ferdinand III, marking one of the largest and most complex operations of his reign. With Seville taken, Castile gained a dominant position in the Guadalquivir valley and greatly reduced Muslim-held territory in Iberia.
Ferdinand III died in Seville on 30 May 1252, leaving a significantly expanded and more unified kingdom to his heir, Alfonso X. By this point, Córdoba and Seville were firmly in Castilian hands, and Granada remained as a smaller, tributary Muslim state.
In 1671, Ferdinand III was canonized as a saint, reinforcing his later image as a model Christian ruler and conqueror. This religious recognition helped cement how his conquests—especially Córdoba (1236) and Seville (1248)—were remembered within Spanish historical tradition.
Ferdinand III of Castile's conquest of Córdoba and Seville (1217–1252)