The question did not take this shape from the beginning. When Frederic first intervened in Lombardy he came to protect the smaller cities against the imperialist ambitions of Milan, to restore the public peace, to investigate innumerable complaints of force and fraud. Many of the cities hailed him as a deliverer; against him were only the clients of Milan, or those who, on a humbler scale, aspired to emulate her policy. Even so it was no easy matter to chastise the most insignificant of the contumacious communes; and Milan, who refused point-blank to give satisfaction for her lawless acts of conquests, or even to renounce what she had won, could not safely be attacked. Two circumstances were against the Emperor. Any war against the Lombards must be a war of sieges; but the military science of the age was more skilful in defence than in attack. And no war could be carried to a prosperous conclusion without Italian help; for it was impossible to interest the German princes in the wars of Italy, or to exact substantial help from them. The first of these difficulties Frederic Barbarossa never overcame. With the second he was more successful in the middle period of the conflict (1158-1162); and it was then that the representatives of Lombard independence were most nearly overwhelmed. In 1158 he came back from Germany to besiege Milan, having carefully concluded treaties with her rivals in Lombardy, in the Mark of Verona, in Emilia and the Marches. With their help he starved the impregnable city into a surrender on terms dictated by himself. In these there was nothing to excite suspicion or alarm. It was a matter of course that the Milanese should take the oath of allegiance and emancipate the enslaved cities. He stipulated further for a palace in the city, and for the restitution of all imperial prerogatives (_regalia_) which the consuls had usurped; but the full import of these latter articles only became clear some two months later, when he announced his future policy at a Diet held on the plain of Roncaglia. He disclaimed the intention of ruling as a tyrant, but demanded that his lawful rights should be respected. As guardian of the public peace, he would permit no private wars to be waged and no leagues to be formed among the cities. As lord of the land, he claimed, under the title of _regalia_, a formidable list of rights and dues which the jurists of Bologna had compiled at the expense of much historical research. It included the nomination of the highest magistrate in every city; the supreme jurisdiction in appeals and criminal causes; the control of mints, markets, and highways; and rights of purveyance and taxation. Some of these had been in abeyance from time immemorial; most of them had been exercised by the cities for more than fifty years. Frederic held that no prescription could avail against the Crown; and, if this attitude seemed more appropriate to a Justinian than to a King of the Lombards, there was still something to