He became king of Castile in 1217 and of Leon in 1230, a union of  kingdoms that was henceforth unbroken. His reign was of the greatest importance in Spanish history, for he undertook the campaigns which wrested the greater part of Andalusia from the Moors and incorporated it in the Christian state. Ferdinand founded the university of Salamanca and perhaps had a part in the beginning of that of Valladolid. At his death he was popularly acclaimed a saint, but he was not formally recognised as such until 1671 by Pope Clement X. 
 

Source: Leo van de Pas