His mother, Judith, was a Guelph (see Guelphs), and Frederick frequently acted as a mediator between his Hohenstaufen uncle, Conrad, and his Guelph cousin, Henry the Lion. Prior to his death Conrad III named Frederick as his successor, hoping that Frederick's reign would end the discord between the rival houses of Hohenstaufen and Guelphs. Frederick's coronation as emperor in Rome was delayed by unrest in Germany and by the revolutionary commune of Rome (1143–55), headed by Arnold of Brescia, which controlled the city. In 1152, Frederick pacified Germany by proclaiming a general land peace to end the anarchy, and in 1156 he satisfied Henry the Lion by restoring the duchy of Bavaria to him, at the same time making Austria into a new duchy as a counterweight to Henry's power.
In Italy, Frederick's policy was to restore the imperial power, which had virtually disappeared as a result of neglect by previous emperors. It was thus necessary for him to conciliate the pope. In a treaty (1153) with Pope Eugene III, Frederick promised to assist him against Arnold of Brescia and against the powerful Normans in Sicily. Frederick entered Italy in 1154 and was crowned in Rome (June 18, 1155) amid hostile demonstrations. The reluctance of his troops to remain in Italy forced him to return to Germany without assisting the new pope, Adrian IV, against King William I of Sicily. Adrian, obliged to ally himself (1156) with William, turned against Frederick.
At the Diet of Besançon (1157) the papal legate presented a letter that Frederick interpreted as a claim by the pope that the empire was a papal fief. Frederick replied in a manifesto that he held the throne "through the election of the princes from God alone" and prepared to invade Italy, where Milan had begun the conquest of Lombardy. Adrian explained that he had not intended that interpretation of his words, but Frederick entered Italy, seized Milan, and at the Diet of Roncaglia (1158) laid claim, as emperor and king of the Lombards, to all imperial rights, including the appointment of an imperial podesta, or governor, in every town.
The rapacity of his German officials led to the revolt (1159) of Milan, Brescia, Crema, and their allies, secretly encouraged by Adrian IV. After a long siege, Frederick stormed and burned Milan (1162). Moreover he set up an antipope to Adrian's successor, Alexander III, who excommunicated him. Frederick withdrew temporarily, but returned in 1166, captured Rome, and was preparing to attack the pope's Sicilian allies when his army was decimated by an epidemic.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.