About Alfonso X of Castile:
Alfonso X was the King of Castile, León and Galicia from 30 May 1252 until his death. During the Imperial election of 1257, a dissident faction chose him to be King of the Romans (Latin: Rex Romanorum; German: Römisch-deutscher König) on 1 April. He renounced his imperial claim in 1275, and in creating an alliance with England in 1254 his claim on Gascony also.