The result of the League’s vigorous policy was entirely successful, and compelled the unscrupulous Valdemar, who found himself shortly in an awkward corner, to collect all the money that he could and depart on a round of visits to the various courts of Europe. He left his people to the fate he had prepared for them, and during his absence Copenhagen was sacked, and the Danes driven to conclude the Treaty of Stralsund that placed the League in control of all the fortresses along the coast of Skaania for fifteen years. The Hansa had now acquired the supremacy of the Baltic, and because the duty of garrisoning fortresses and patrolling the seas required a standing army and navy, the League of northern towns did not, like those in South Germany, Italy, or France, melt away as soon as temporary safety was achieved. Each city continued to manage its own affairs, but federal assemblies were held, where questions of common taxation and foreign policy were discussed, and where those towns that refused to abide by decisions previously arrived at were ‘unhansed’, that is, deprived of their privileges. Even Emperors, who condemned leagues on principle from old Hohenstaufen experience, respected if they disliked ‘the Hansa’ that carried through national police-work in the north of which they themselves were quite incapable. The Emperor Charles IV, when he visited Lübeck, addressed the principal civic officials as ‘My lords!’ and when, suspicious of this flattery, they demurred, he replied, ‘You are lords indeed, for the oldest imperial registers know that Lübeck is one of the five towns that have accorded to them ducal rank in the imperial council.’ The chronicler adds proudly that thus Lübeck was acknowledged the equal of Rome, Venice, Florence, and Pisa. In the latter half of the fourteenth century the Hanseatic League stood at the height of its power; for though the political genius of Queen Margaret, daughter of Valdemar III, succeeded in uniting Denmark, Norway, and Sweden by the agreement called ‘the Union of Kalmar’, and also forced the Hansa to surrender the fortresses on the Skaania coast; yet even the foundation of this vast Scandinavian Empire could not shake German supremacy over the Baltic. Under Margaret’s successors the Union of Kalmar degenerated into a Danish tyranny; and because it was the result of a dynastic settlement and not of any national movement it soon came to shipwreck amid general discontent and civil wars. The Hanseatic League itself, though it lingered on as a political force through the fifteenth century, gradually declined and lost touch with the commercial outlook of the age. The decline may be traced partly to the fact that there was no vigorous national life in Germany to feed the League’s vitality, but also to a steady tendency for towns to drift apart and become absorbed in the local interests of their provinces.