A doubtful peace was now concluded with the Danes, but was soon broken by their renewed plunderings of Hanseatic vessels and the obstacles placed by them upon traffic. Another passage at arms was required. The ensuing conflict was the greatest and most glorious ever fought, not only by the Hansa, but by Germany, upon the sea. In 1367 deputies from the Prussian, Wendish, and Netherlandish cities assembled in the city hall of Cologne and there prepared those memorable articles of confederation which decreed another war with King Waldemar of Denmark; stipulated the levying of a definite contingent of troops on the part of the contracting cities; provided for a duty on exports to defray the expenses of the campaign; and draughted letters of protest to the Pope, to Emperor Charles IV, and to many of the German princes. That auspicious day marks a turning-point in the history of the Hanseatic League, and was fraught with high importance to the whole German empire. The preliminary history of the Hansa here ends and its brilliant epoch begins. The warships of the cities and their army so thoroughly vanquished Denmark that, after two years of warfare, the Danish royal council and the representatives respectively of the municipalities, the nobility, and the clergy despatched a commission of thirty-two to Stralsund to sign a treaty, ostensibly in the name of their fugitive ruler--a treaty which may justly be said to mark the climax in the development of the power of the burghers of Germany. The treaty not only provided for considerable concessions in matters of navigation and intercourse, but also conceded to the members of the Cologne confederation, comprising about sixty Hansa cities, the right to occupy and to fortify for a period of fifteen years the four chief castles on Skane--Helsingborg, Malmo, Scanov, and Falsterbo--commanding the sound, the most important maritime highway traversed by the Hanseatic vessels. But the most extraordinary privilege granted by this treaty was that making the subsequent election of a king for Denmark subject to the approval of the confederation--thus assigning to the burghers a right such as no king or emperor of that time exercised over a foreign state. The confederates, however, wisely declined to avail themselves of this dangerous prerogative, not only for political reasons, but also because of the clever negotiations of the youthful queen Margaret, the daughter and heir of Waldemar, who, by the union of Kalmar in 1397, became invested with the triple crown of Denmark, Norway, and Sweden. The fact remains, however, that the Hansa for the ensuing century and a half maintained its title as the foremost of maritime and as one of the principal political powers--and that entirely unaided and without the sanction of kaiser or empire.