The Hansa was a major power in the Baltic region during the Middle Ages. German merchants controlled many of the towns as they were members of the councils. Many kings and princes felt threatened by the influence of the League and feared that the autonomy of the nations would decrease or disappear altogether. The Danes were afraid that they would lose their leading position. This situation led to the establishment of the Kalmar Union at the end of the 14th century. The aim was to resist the power of the Hanseatic League.
The members of the Hansa, though, did not want any one country to grow strong enough to threaten the Hanseatic influence. Therefore, in conflicts and wars, the League would support the second strongest power in order to balance the situation. In 1360 and in 1361, Valdemar Atterdag conquered Skåne, Öland and Gotland. The Hanseatic towns started a war against him to try to stop Denmark from becoming too powerful.
The Hansa and the kings and princes of the region competed for control in the Baltic region during the Middle Ages. The merchants wanted to avoid wars - their trade depended on it. They also wanted to get rid of the pirates.