The rise of the commune was partly due to the Feudal system, which had its origin in the “fee” or tenure in land. As the system came to be worked out, the tenant held in fief from an overlord, who in turn held from some more powerful overlord and so on up to the King. When the latter went to war, the word was passed down and each overlord had to bring his quota of men, which he made up from the levies of the overlords below him. It thus became an automatic method of raising an army, of which the lowest knight with his few followers was the unit. On the other hand, the ease with which the method could be put in operation and the need of constant preparation for it, maintained a condition of warlike feeling, that in the absence of a great war broke out in jealousy and strife among the several constituent parts of the system. It was to guard against the inevitable miseries of this constant turmoil that the merchants and artisans built their homes and shops around some burg or castle, to the lord of which they looked for protection, walls of defence being gradually built around the city, until it became fortified with the castle as a citadel. The benefits were mutual. Commerce and trade could be pursued in comparative peace, while the lord in return for his protection would receive a portion of the profits to finance his various expeditions or intrigues. To consolidate their influence the merchants formed themselves into merchant gilds, while the citizens established craft-gilds in the various trades. Thus gradually both commerce and trade spun a network of peaceful activity and comparative stability over the otherwise troubled world, knitting together its remotest parts. For while the agricultural population was tied to the soil, and passed with its transfer from one owner to another, the condition of commerce and to some extent of trade was fluent. Merchants travelled and had their agents in distant countries; and even the artisan might move from place to place and enroll himself for the time being in the local gild of his craft. And the merchants became also the bankers of their time: those of Lombardy, for example, loaning money to kings as well as to other merchants; the memory of which is preserved in “Lombard Street,” in London’s financial centre. These merchants had become wealthy by trading in the merchandise from the East and increased their wealth by distributing the merchandise throughout the West. Milan, therefore, speedily grew in importance because she commanded the roads leading over the passes of the Alps. Thence the chief stream of commerce led at first through Provence. Later, German cities like Augsburg and Nuremburg, became powerful and prosperous on the road to such northern ports as Lübeck and Hamburg, while the Rhine became the highway of commerce to Bruges, Ghent, and Brussels.