Against the municipality of Rome and the king of Sicily, Eugene III and Adriano IV popes found an ally in Frederick I of Swabia, who, having met in Constance with the legates of Eugene III, swore help against those enemies and made a commitment to go to Rome to receive the imperial crown. And Frederick kept his promise, in 1154. He varied the purposes: to reaffirm his authority over the papacy which proved, yes, friend, but was putting too much open his doctrine and ambition of primacy over the other power, the empire ; resume the ancient enterprise, in southern Italy, where the Norman kings were now masters; putting things back together in the kingdom which was still the key to the vault of the empire in Italy, but now it looked like a ruined building. They were gone, like a century or two before, the great counts and marquises the powerful archbishops, arbitrators of the crown. But cities were taking its place. Matilde was also dead and her family disappeared. But the spirit of the Canossa family by now animated Florence, which grew precisely in the protection of the great countess and destined to embody, more perhaps than any other Italian city, the municipal suspicion of the empire, the aversion of the Italians to the domination of strangers and , as they will later say about the Germans of Henry VII in an official document, “repugnant for ancient facts and bearing, for language and customs, for spirit and will”.
Until then, the empire had also contributed to creating this new political-social order, in Italy as in Germany. Lothair had tried to put some shelter. But everything went on as before. Until the feudal forces of opposition, the energetic personality of the new emperor, a certain awareness of the Germanic people that it was his own interest at stake, arose to block the path to the new city society. Federico Barbarossa armed himself with his strength and his law; he called or welcomed around him feudatories, animated by hatred against vassals and plebeians, and jurists, who flocked to defend the established right and, for the moment, the strongest; it also stimulated German national self-love and the feeling of a German right and honor committed to Italy; on the peninsula it became the center of all the offended interests, of feudatories, bishops, counts, small towns obscured or threatened by the larger ones (Pavia, Lodi, Como etc.); it flattered the hopes of powerful maritime cities which counted on the strength of the Germans against each other and expected commercial advantages from the imperial conquest of Sicily.
He made six expeditions, starting from 1154. In upper Italy, Milan was the key to the vault. But Federico didn’t have the strength to face it. He turned to Rome, gave the pope Arnaldo destined for the stake, took the crown, won the Romans: but neither he nor the pope could enter the city. He then moved towards the kingdom, where Ruggiero II had happened to William I in 1154, and the barons of the continent were in rebellion, the Sicilian nobility awaiting events. Pope Adrian, an English native, who did not want to recognize the new king, accompanied the emperor. But William, as he faced internal enemies, so too external ones. Barbarossa, having arrived in Campania, had to go back. The pope then, not happy with Barbarossa, worried about the return of Byzantium which had occupied Ancona, the city of the Church, and defeated the Norman fleet in Brindisi, he concluded the peace of Benevento with the kingdom (1156), undertaking to crown William and invest him with Sicily, Puglia and Capua, and confirming his ecclesiastical prerogatives. Peace also came between Byzantium and the Norman kings. And in Rome the Romans arranged themselves with the pope. Who thus, secure at home and behind, assumed a different attitude with the emperor as well. The papacy returned to reaffirm its high right over the imperial crown, to consider it as a “benefit” to be assigned and who was invested as a beneficiary and subject. And he could now become the center of all the oppositions to the empire and to the Germans, that is, the Normans of the south, the municipalities of the north and of the center. In Rome the pontiff could not tolerate an independent municipal system; but outside of Rome, a policy of communal autonomy or liberty might well correspond to his own interest. Raised in Italy and nourished by Italian life, the papacy had a sense of Italian reality more than the German lord.
According to Picktrue, the imperial policy of claims against the cities was also intensified. New and major expedition in 1158: and Milan, besieged, had to capitulate. The Bolognese doctors and a large college of city judges met in Roncaglia, by the will of the emperor, and determined which gifts were to be recovered. And immediately the imperial officials began to get their hands on these rights again. But the storm broke out. Cities rose up. And since those imperial claims were also directed towards the goods of the Countess Matilde, relations with the pope also worsened.