 Indeed, Conrad could stable his rule, however, the Imperial supremacy in Italy remained contested.The cities first demonstrated their increasing power during the reign of the Hohenstaufen Emperor Frederick Barbarossa (1152–1190), whose attempts to restore imperial authority in the peninsula led to a series of wars with the Lombard League, a league of northern Italian cities, and ultimately to a decisive victory for the League at the Battle of Legnano in 1176, which forced Frederick to recognize the autonomy of the Italian cities.Frederick's son Henry VI actually managed to extend Hohenstaufen authority in Italy by his conquest of the Norman Kingdom of Sicily, which comprised Sicily and all of Southern Italy.