This would seem to have been the turning-point in the long welter of Italian history. The Longobard conquest under Alboin forced on the process of driving the older inhabitants into the cities. The Ostrogothic kings, while they unwalled the towns they captured, had fortified Pavia, which was able to resist Alboin for four years, thus giving the other towns their lesson; and as he advanced the natives fled before him to Venice, to Genoa, to the cities of the Pentapolis, to Pisa, to Rome, to Gaeta, to Naples, and to Amalfi.[501] Above all, the cities of the coast, still adhering to the Greek Empire, and impregnable from land, were now allowed to retain for their own defence the revenue they had formerly paid to Constantinople; Naples won the right to elect her own dukes; and Venice won the status of an equal ally of Byzantium.[502] Thus once more there began to grow up, in tendency if not in form and name, republics of civilised and industrious men, in the teeth of barbarism and under the shadow of the name of empire.[503] Even in the eighth and ninth centuries the free populations of Rome and Ravenna were enrolled under the four heads of _clerici_, _optimates militiæ_, the _milites_ or _exercitus_, and the _cives onesti_ or free _populus_.[504] Beneath all were the great mass of unfree; but here at least was a beginning of new municipal life. The Longobards had not, as has been so often written, revived the spirit of liberty; conquest is the negation of the reciprocity in which alone liberty subsists; but they had driven other men into the conditions where the idea of liberty could revive; and in so far as "Lombard" civilisation in the next two hundred years distanced that of the Franks,[505] it was owing to the revival of old industries in the towns and the reactions of the other Italian cities, no less than to the renewed growth of rural population and agriculture.