Alfonso IX, 1171–1230, Spanish king of León (1188–1230), son and successor of Ferdinand II. He conquered from the Moors several cities in Estremadura and was frequently at war with Alfonso VIII of Castile. His marriages with Teresa of Portugal and Berenguela of Castile were both annulled by the pope. He defeated (1230) the Moors at Mérida. His son by Berenguela, Ferdinand III, reunited (1230) León and Castile.