By his death in 1216, Pope Innocent III had increased papal power and extended the influence of the papacy over European monarchs. It was his belief that the Papal States were under threat from the expansionist plans of the Holy Roman Emperor, Henry VI, who had already claimed the kingdom of Sicily and installed feudal lords in the Papal States. After Henry VI’s death in 1197, Pope Innocent III became guardian to his infant son Frederick II; the empire was in disarray and Innocent III exploited this by evicting the empire’s feudal lords and diluting the power of the monarchy by decree, stating that the pope had supremacy over kings and it was the pope’s right to have final authority, as God’s anointer, over elected rulers. Frederick II was frequently at war with the papacy and his son Conrad IV’s trails continued when he tried to assert his power against Pope Innocent IV – he was excommunicated in 1254. Conrad’s death was followed by the Interregnum, when there was no Emperor and the power of the papacy was undisputed. But in 1273 Rudolph of Habsburg was elected king of the Romans and was determined to challenge Innocent III’s legacy by reunifying with Sicily.