Within Europe commerce gradually extended its scope in spite of the almost insuperable difficulties. The roads were still so miserable that wares had to be carried on pack-horses instead of in wagons. Frequently the merchant had to risk spoiling his bales of silk in fording a stream, for bridges were few and usually in urgent need of repair. Travel not only was fraught with hardship; it was expensive. Feudal lords exacted heavy tolls from travelers on road, bridge, or river. Between Mainz and Cologne, on the Rhine, toll was levied in thirteen different places. The construction of shorter and better highways was blocked often by nobles who feared to lose their toll-rights on the old roads. So heavy was the burden of tolls on commerce that transportation from Nantes to Orleans, a short distance up the River Loire, doubled the price of goods. Besides the tolls, one had to pay for local market privileges; towns exacted taxes on imports; and the merchant in a strange city or village often found himself seriously handicapped by regulations against "foreigners," and by unfamiliar weights, measures, and coinage. Most dreaded of all, however, and most injurious to trade were the robbers who infested the roads. Needy knights did not scruple to turn highwaymen. Cautious travelers carried arms and journeyed in bands, but even they were not wholly safe from the dashing "gentlemen of the road." On the seas there was still greater danger from pirates. Fleets of merchantmen, despite the fact that they were accompanied usually by a vessel of war, often were assailed by corsairs, defeated, robbed, and sold as prizes to the Mohammedans. The black flag of piracy flew over whole fleets in the Baltic and in the Mediterranean. The amateur pirate, if less formidable, was no less common, for many a vessel carrying brass cannon, ostensibly for protection, found it convenient to use them to attack foreign craft and more frequently "took" a cargo than purchased one. [Sidenote: Venice] These dangers and difficulties of commercial intercourse were due chiefly to the lack of any strong power to punish pirates or highwaymen, to maintain roads, or to check the exactions of toll- collectors. Each city attempted to protect its own commerce. A great city-state like Venice was well able to send out her galleys against Mediterranean pirates, to wage war against the rival city of Genoa, to make treaties with Oriental potentates, and to build up a maritime empire. Smaller towns were helpless. But what, as in the case of the German towns, they could not do alone, was partially achieved by combination. [Sidenote: The Hanseatic League. Towns in the Netherlands: Bruges]