The free cities derived their strength from industry, and had nothing in common with the nobles of the surrounding country. Broadly speaking, the population of the towns included what remained in Italy of the old Roman people. This Roman stock was nowhere stronger than in Florence and Venice—Florence defended from barbarian incursions by her mountains and marshes, Venice by the isolation of her lagoons. The nobles, on the contrary, were mostly of foreign origin—Germans, Franks, and Lombards, who had established themselves as feudal lords in castles apart from the cities. The force which the burghs acquired as industrial communities was soon turned against these nobles. The larger cities, like Milan and Florence, began to make war upon the lords of castles, and to absorb into their own territory the small towns and villages around them. Thus in the social economy of the Italians there were two antagonistic elements ready to range themselves beneath any banners that should give the form of legitimate warfare to their mutual hostility. It was the policy of the Church in the twelfth century to support the cause of the cities, using them as a weapon against the Empire, and stimulating the growing ambition of the burghers. In this way Italy came to be divided into the two world-famous factions known as Guelf and Ghibelline. The struggle between Guelf and Ghibelline was the struggle of the Papacy for the depression of the Empire, the struggle of the great burghs face to face with feudalism, the struggle of the old Italie stock enclosed in cities with the foreign nobles established in fortresses. When the Church had finally triumphed by the extirpation of the House of Hohenstaufen, this conflict of Guelf and Ghibelline was really ended. Until the reign of Charles V. no Emperor interfered to any purpose in Italian affairs. At the same time the Popes ceased to wield a formidable power. Having won the battle by calling in the French, they suffered the consequences of this policy by losing their hold on Italy during the long period of their exile at Avignon. The Italians, left without either Pope or Emperor, were free to pursue their course of internal development, and to prosecute their quarrels among themselves. But though the names of Guelf and Ghibelline lost their old significance after the year 1266 (the date of King Manfred’s death), these two factions had so divided Italy that they continued to play a prominent part in her annals. Guelf still meant constitutional autonomy, meant the burgher as against the noble, meant industry as opposed to feudal lordship. Ghibelline meant the rule of the few over the many, meant tyranny, meant the interest of the noble as against the merchant and the citizen. These broad distinctions must be borne in mind, if we seek to understand how it was that a city like Florence continued to be governed by parties, the European force of which had passed away.