It was this fatal insistence upon Italian authority that brought disaster upon Frederick and all his house, and ultimately upon the empire as well, and on the entire German race. The Italians had been quite content to call themselves subjects of a Holy Roman Empire which extended but vaguely over Europe, and whose chief took his title from their ancient city and only came among them to be crowned. They looked at the matter in a wholly different light when Frederick regarded his position seriously, and interfered in their affairs with the strong hand, crushing their feuds and exacting money tribute. Rebellion was promptly kindled, and for twenty years one German army after another dwindled away in the passage of the Alps, wasted under the fevers of Italian marshes, or was crushed in desperate battle. By the treaty of Constance, in 1183, Frederick confessed the one defeat of his career. He acknowledged the practical independence of the Italian cities.[1] CITIES AND KINGS The Emperor had in fact encountered a power too strong for him. He had been struggling against the beginnings of modern democracy, a system stronger even in its infancy than the ancient rule of the aristocracy which it has gradually supplanted. The resistance of Italy came not from its knights and lords, but from its great cities, which had been slowly growing more and more self-reliant and independent. The rise of these city republics of the Middle Ages cannot be fully traced. Everywhere little communities of men seem to have been driven by desperation to build walls about their group of homes and to defy all comers. As it was in Italy that the ancient Roman civilization had been most firmly established and the barbarian dominance least complete, so it was in Italy that these walled towns first asserted their importance. Venice indeed, protected by her marshes, we have seen establishing a somewhat republican form even from her foundation. She and Genoa and Pisa defended themselves against the Saracens and built ships and grew to be the chief maritime powers of the Mediterranean, rulers of island empires. They fought wars against one another, and Pisa was overwhelmed and ruined in a tremendous conflict with Genoa. Genoa's fleets carried supplies for the first crusaders. In later crusades, when the deadly nature of the long journey by land was more clearly known, the wealthy maritime republics were hired to carry the crusaders themselves to the East--and profited vastly by the business.