The rise of the Hanseatic League was essentially a political event, it being little more than a federation established by German towns among themselves to maintain by political action that status in European trade which they had won as economical changes took place. So far as furthering its trade interests was concerned, the political organisation of the League was far more effective than that of the surrounding territorial states. While royal and ducal governments had to deal with dynastic entanglements, greed for military glory, social privileges and territorial disintegration, the Hanseatic League was only concerned about its trade interests. Acquisition and defence of its foreign privileges was the raison d'être of the League which of the League which had no wish to become a constitutional federation, waging wars only in special circumstances. The Hanse towns held a great&ee weapon in their warships, their naval skills and readiness to engage in naval battle were one of the causes of Hanseatic greatness. The main reasons for Hansa's success in its military affairs were the complete subordination of military matters to political leadership, the ability to rejoin threads of negotiation at any time, even during fighting and to complete negotiations successfully by means of inherently self-assured and consistent diplomatic skill.
The League owed much of its riches and power to herring but as masters of the Belt and the Sound the Danes were able, if they chose to, greatly to harass Hanseatic traders and fishermen. The Hanse towns fought several wars against Denmark, the first of which took place in 1227 and ended with Denmark beaten. In 1249, when Eric II attacked some of Lübeck's ships, merchant towns responded by sacking Copenhagen. However, the most important of wars between the Hansa and Denmark was started by Waldemar III who became the king of Denmark in 1326. His aim was to nationalise the country and thus to drive away the foreigners who used Denmark for their own commercial ends. Waldemar interfered with Hansa's fishing rights in Scania, broke contracts made by his predecessors and demanded extortionate fees for renewal of time-honoured privileges. The Hanseatic towns responded by laying an embargo on all Danish goods and forbidding all interaction with her. In 1362 they plundered Copenhagen but due to an error of judgement by the commander of the Hanseatic Fleet, they were cruelly defeated. Waldemar was determined to totally break the League but eventually was forced to plead for peace when by the end of 1396 Denmark was totally exhausted. The League was able to dictate the peace talks, its demands, for example the claim of receiving two-thirds of the revenue in Scania for 15 years, were all granted. Thus the Hanse supremacy over Scandinavia was established.
In addition to Denmark, the Hanseatic League had a troubled relationship with Russia where matters came to a head when Tsar Ivan the Terrible cast his jealous eye on the rich town of Novgorod, this lead to the Hanseatic merchants who lived there being taken prisoner. However, not all League's relationships with other nations were as difficult as these two. In France, for example, no one threatened its position but instead the Hansa was a great power. Louis IX proposed an alliance with the merchant towns against England, Charles VIII further enlarging concessions granted by his father, recording that in case any difficulties arose due to obscurities of phrase in a contract between the League and a Frenchman, these should always be interpreted to the advantage of the Hansa. Nowhere was the League's power as great as in England, in particular during the reign of Edward III. The king's resources were strained to the utmost by the wars with France and without the help of German capital the victories at Crecy and Poitiers might have never happened. Sometimes the League was even spoken of as an ally of the English kings.