municipal unions, which, under the leadership of the free and
centrally located city of Lubeck, now assumed the energetic
guardianship of maritime commerce, by reason of which they were drawn
from their hitherto isolated position and gradually became fused into
an increasingly compact union.

Already at the close of the thirteenth century the young institution
of the Hansa received its initiation in warfare in a conflict with the
kingdom of Norway, which country was compelled to purchase peace at
the price of new and greater concessions to the league. Soon
thereafter, however, the steady progress of the Hansa met with a
rebuff. Denmark, at that time the foremost power of the North, had for
more than a century endeavored to obtain the supremacy of the Baltic,
at the entrance to which it was so advantageously situated. At one
time Lubeck was for an entire decade forced into a sort of vassalage
to the energetic king Eric Menved of Denmark, although the relations
to the sister-cities of the league, which had never been entirely
severed, were subsequently restored and confirmed by new treaties.
When finally, in A.D. 1361, the Danish king Waldemar Atterdag,
inspired by rapacity and revenge, went so far as to fall upon the
metropolis of the Baltic, the Swedish city of Wisby, in the midst of
peace, and to annex it, thereby inflicting serious losses upon the
resident Low-German merchants, Lubeck once more placed herself at the
head of the Wendish cities and at the diet of Greifswald decreed war
against the ruthless invader. But the expedition proved disastrous,
owing chiefly to the tardiness of the kings of Sweden and Norway, who
had been drawn into the alliance. Nevertheless, the unfortunate
admiral of the Lubeck fleet, Johann Wittenborg, who also enjoyed the
rank of burgomaster of the Hanseatic city, was put to the axe in the
public market-place of Lubeck in expiation of his failure.