Alphonso X

Alphonso X of Castile and Leon, called El Sabio, or "the learned" (born 1221, died 1284, reigned 1252-1284), was a writer, of considerable scientific fame, based on his study of astronomy and the Ptolemaic cosmogony as known to him through the Arabs.

Alphonso spent much effort and money persuing his claim to the title of (Holy Roman) Emperor through his descent from the Hohenstaufen family through his mother, a daughter of the emperor Philip of Swabia, after the death of Conrad IV in 1254. He gained the emnity of nobles and commoners by de-basing the coinage to pay for his activities.

His second son, Sancho, claimed to be heir, in preference to the children of Ferdinand de la Cerda, Alphonso's elder brother. When Alphonso tried to unite the nation in a crusade against the Moors, Sancho and the nobles supported the Moors.

Alphonso died defeated and deserted at Seville, leaving a will by which he endeavoured to exclude Sancho from the succession.