The German emperors of the Hohenstaufen line, who had inherited the kingdom of Sicily from its Norman rulers in 1197, had continually attempted to consolidate their more long-standing claims to northern Italy as well—an ambition which was vehemently opposed by many northern Italian states and by the Papacy. The resulting struggle between the Papacy and the Holy Roman Empire split the loyalties of many Italians and led to factionalism, the resulting factions being termed the Guelphs and Ghibellines. The death of the German emperor Frederick II of Hohenstaufen in 1250 in the midst of this struggle eventually found his legitimate grandson and heir as King of Sicily, Conradin, in southern Germany, and Sicily under the rule of Conradin's uncle, Manfred of Sicily, the illegitimate son of Frederick II. Manfred ruled in Sicily at first along with his legitimate half-brother, Conrad IV (Conradin's father), and after Conrad IV's death from malaria in 1254, as regent for Conradin. However, in 1258 Manfred declared himself king, despite Conradin's claim, purportedly because of rumors of Conradin's death.