Conrad IV was succeeded as duke of Swabia by his only son, two-year-old Conradin. By this time, the office of duke of Swabia had been fully subsumed into the office of the king, and without royal authority had become meaningless. In 1261, attempts to elect young Conradin king were unsuccessful. He also had to defend Sicily against an invasion, sponsored by Pope Urban IV (Jacques Pantaléon) and Pope Clement IV (Guy Folques), by Charles of Anjou, a brother of the French king. Charles had been promised by the popes the Kingdom of Sicily, where he would replace the relatives of Frederick II. Charles had defeated Conradin's uncle Manfred, King of Sicily, in the Battle of Benevento on 26 February 1266. The king himself, refusing to flee, rushed into the midst of his enemies and was killed. Conradin's campaign to retake control ended with his defeat in 1268 at the Battle of Tagliacozzo, after which he was handed over to Charles, who had him publicly executed at Naples. With Conradin, the direct line of the Dukes of Swabia finally ceased to exist, though most of the later emperors were descended from the Staufer dynasty indirectly.