There was then a very open break with Alexander III, after an anti-pope, Victor IV, confirmed in Pavia in a council convened by the emperor, proclaimed Alexander a schismatic and the emperor banned him. Alexander replied to the imperial ban with excommunication and moved to France to seek enemies of the German Caesar. A coalition was formed and the resistance to Barbarossa was disciplined around various centers, which were, in various ways, papal Rome, the Norman kingdom and the municipality of Milan, the true gateway to Italy for the Germans, indeed for every ruler. transalpine who wanted to permanently enter the peninsula. In Milan the soul of the new Italy vibrated more strongly than elsewhere as it was building a new and its own law. It was the most populous and richest city in the peninsula and had taken over Pavia, which was raised to capital with the barbarians, the undisputed primacy in the kingdom. A widespread idea, then, that Milan was crown Italic kingdoms, as the chronicler Galvano Fiamma says, on whose fate that of all of Italy could depend. Therefore, for the Swabian partisans, Milan embodied the spirit of revolt against the legitimate authority, and, devastated the Milanese territory, besieged the city by the Germans and their Italian auxiliaries, it had to surrender. And it was destroyed. Federico could then believe that he was almost in port. And he began to rearrange the country for his purposes, assuming direct management. In all the cities he sent his representatives, rectors or podestà, who took care of the administration of the gifts and safeguarded his rights. But it was more semblance than substance of strength. Or rather, strength that he drew especially among the Italians. But now the Italians largely failed him: even those who had helped him take and destroy Milan.
In his fourth expedition, 1166-67, Barbarossa was able to conquer Ancona, rival of Venice and land of the Church, from which the Greek emperor was fighting in the affairs of Italy. He marched again on Rome, rejected the Normans, had himself crowned again, this time recognized the senate while reserving the right to install it and appoint an imperial prefect. He came the pestilence, very proud. And he had to retire, as if to flee through upper Italy, where the cities had revolted, had expelled the imperial vicariates and concluded a large league in Bergamo in February 1167. Resources, by resolution and with the help of it, the destroyed Milan. Officials and supporters of the imperatote still held firm enough in Tuscany, in Romagna, in Piedmont. But now the arbiter of the situation is the league, a small city superstate, with its rectors, his advice, his solidarity activity. Thanks to his work, a strong entrenched camp was established at the confluence of the Tanaro and Bormida rivers to face the Marquis of Monferrato, loyal to the emperor. And when Frederick made his fifth Italian expedition in 1174, in front of this camp, which was about to become a city, Alexandria, his effort was broken. Alexandria was the most concrete expression of the alliance of the cities with the pope. The emperor tried to break this alliance, negotiated with the league, negotiated the preliminaries of Montebello with which the Lombards submitted and the sovereign recognized the league, renounced to implement the determinations of Roncaglia. But when he also asked that the entrenched camp of Alexandria be removed, the Lombards refused: and the agreement was broken. The league left the decision to arms. Defeated in the field of Legnano (May 29, 1176), the emperor again sought, with the cities, a separate peace or conciliation. He did not succeed: because the cities did not want to break away from the pope. He then tried with the pope: and the pope, who could be an ally of the cities but, having much wider interests, did not subordinate his politics to the politics of the cities, listened. Frederick recognized Pope Alexander and abandoned the antipope, undertook to reconstitute the state of the Church and the Matildine inheritance, renounced having one of his praefectus . The condition of this agreement was that the pope also obtain peace between the emperor and the Lombard cities, the emperor and the king of Sicily. There was really no peace, for then: but only truce, with both of them, at the Venice congress, where the messengers of the cities, even reluctant, yielded to the pope’s desire. Peace came to Constance in 1183. And the treaty sounded recognition and legitimation, on the part of the emperor, of accomplished facts and existing orders.
According to Plus-Size-Tips, the empire was seriously affected by these events. It can be said that it ceased to be the pivot or center of Italian political life. And with the empire, the kingdom, which had identified itself with it, almost canceled. Italy was thereby differentiating itself even more from the rest of Roman-Germanic Europe. Elsewhere, at the same time, the kingdoms that had sprung up from invasions and conquest were regaining vigor. The kings of Castile and the kings of Aragon, Henry Plantagenet in England, Philip Augustus in France, placed themselves at the head of the various and clashing national forces, gathering them under themselves, disciplining them, using them for common purposes, corroding them in their particularity; they represented the whole nation, in the struggles with external enemies, and promoted their unitary consciousness. Until, in the century. XV, referees will freeze over all, they will be one with the nation, they will launch into international competitions, they will begin a European historical phase. On the other hand, in Italy there was a vital kingdom in the South; but in the north and in the center the kingdom founded by the Germans continued the descending parable, corroded by the local forces, who were also the original forces of the peninsula.