Indeed, definition was no easy matter, for medieval towns differed infinitely in size, in government, and in the ingredients of their population. In one respect they are all alike; the most energetic and influential, though not necessarily the greater number, of the inhabitants are artisans or traders. But side by side with the industrial colony stand older interests, which often struggle hard against the ascendancy of commerce. In the town or near it there may be an abbey or a castle or a cathedral or a royal palace, to which the very existence of the burgess community is due. The townsmen, profiting by the custom and the protection of the great, have grown rich and independent; they have bought privileges or have usurped them. But they have still to reckon with the servants, the retainers, and the other partisans of a superior always on the watch to recover his lost rights of property and jurisdiction; the forces of the common enemy are permanently encamped within the walls. Again, if the town lies on a frontier or in newly-conquered country, it will be as much a fortress as a mart; a number of the residents will be knights or men-at-arms who hold their lands by the tenure of defending the town; and these burgesses will be naturally indifferent to the interests of the traders. Finally, in the Mediterranean lands, with their long tradition of urban society, we find the nobles of the neighbourhood resorting to the town, building town-houses, and frequently caballing among themselves to obtain control of the town's government. Often a long time elapses before the class which conceived the idea of municipal liberty is able to get the better of these hostile forces; and still more often the hardly-won privileges are wrested from those for whom they were intended, are cancelled, or are made the monopoly of an oligarchic ring.