Peter the Cruel, 1334–69, Spanish king of Castile and León (1350–69), son and successor of Alfonso XI. His desertion of his wife, Blanche of Bourbon, for María Padilla and his favors to the Padilla family aroused the opposition of the nobles and led to several rebellions fomented by Peter's illegitimate half-brother, Henry of Trastámara (later Henry II). Peter ruthlessly suppressed the rebellions, but Henry later obtained the help of Aragón, which was already at war with Castile, and France, and in 1366 he invaded Castile with French mercenaries under Du Guesclin. Peter fled, and Henry was crowned king at Burgos in 1366. Peter, however, had allied (1362) himself with England and with the help of Edward the Black Prince, he defeated Henry and Du Guesclin at Nájera (1367). Henry raised a new army with Du Guesclin, defeated Peter at Montiel (1369), and killed him in a duel after the battle. Despite his reputation for cruelty, Peter has many apologists, who see him as a defender of the rights of the commoners and the throne against the turbulent nobles. Peter's daughter Constance married John of Gaunt, who contested Henry II's succession to Castile.