Infante Frederick of Castile (1223–1277), born in Guadalajara, was a younger son of St. Ferdinand III, King of Castile by his first wife, Elisabeth of Hohenstaufen. After the conquest of Seville, unhappy under the rule of his brother Alfonso, he may have participated in the rebellion of his brother Henry in 1255; in any case, he was exiled from Castile in 1260 and joined Henry as a knight errant in Tunis serving under Sultan Al Mustansir against his enemies. Later, he joined the service of King Manfred of Sicily, and fought at the Battle of Benevento (1266). He escaped the defeat there and returned to Tunis. An anti-Angevin revolt in Sicily in 1267 provided an opportunity for him to cross over again, and he helped raise the island for Conradin, while Henry (now Senator of Rome) also declar