It is interesting to note the manner in which this extraordinary influence was secured.  In later mediaeval times all classes of the population were compelled to rely upon self-help.  In other words, they were compelled to replace the defective or insufficient protection afforded by the State by corporate bodies.  Thus the merchants of a Low-German German town, when in search of a common centre of trade, pledged themselves by a solemn oath to a defensive and offensive alliance and mutual furtherance; and wider alliances between the various towns themselves soon followed.  Of all these private commercial associations none attained to greater importance than did the Gothland Company, a society of Low-German merchants who visited Gothland, the centre of commercial activity in the Baltic, for trading purposes.  Here was the seat of the mighty city of Wisby, which contained such wealth that a Danish king once declared that the swine there ate from silver troughs.  Even at the present day the massive ruins of the old city wall and of the eighteen churches which once existed there bear testimony to the former magnitude and grandeur of the city.  The Gothland Company flourished chiefly during the thirteenth century and enjoyed all the privileges of a political power; bearing its own seal, policing the seas, and insisting upon strict compliance on the part of all navigators of the Baltic with the marine laws which it had created.

Parallel with this development was the formation of unions between inland towns, caused by the depredations of robber-knights; the menacing increase of power among the nobility; and by commercial motives of all kinds, as, for example, the necessity of preventing banished criminals and debtors from seeking an asylum in neighboring communities.  Along the entire region from Esthland to Holland, both of which at that time belonged to the German crown, the municipalities united.  In the far-western part of the German empire there was the municipal group of the Netherlands, among which such cities as Amsterdam, Utrecht, and Deventer belonged.  Farther inland was the Rhenish-Westphalian group, consisting of Cologne, Dortmund, Munster, and others, which cities, though somewhat distant from the sea, nevertheless occupy a place of honor as pioneers of German marine commerce.  Between these two western groups and those in the East there was a wide gap extending as far as the mouths of the Elbe and the Weser.  At the entrance to these rivers, however, and along the borders of the Baltic were the great maritime communities, the chief members of the Hanseatic League, including the before-mentioned Wendish group and the cities of Bremen and Hamburg.  Yet not these alone, although they were in some respects the most important.  Inland, the municipal groups extended so as to embrace Berlin, then very unimportant, Perleberg, etc., in the Mark of Brandenburg, the Saxon cities of Magdeburg, Hanover, Luneburg, Goslar, Hildesheim, Brunswick, and others; in the far-eastern