At the climax of their power, the Victual Brothers occupied the island of Gotland, Sweden, in 1394 and set up their headquarters in Visby. They also operated from the Turku archipelago; Knut Bosson, who was the chief of Turku Castle from 1395 to 1398, had allied himself with the people of Mecklenburg, which is why he supported the hijacking activities of the Victual Brothers and allowed them to operate in the area. Maritime trade in the Baltic Sea virtually collapsed, and the herring industry suffered from their depredations. Queen Margaret even turned to King Richard II of England and sought to charter English ships to combat the pirates. From 1395 onwards, Queen Margaret gained the upper hand politically. She united Denmark, Sweden and Norway and formed the Kalmar Union. The Hanseatic League was forced to cooperate with her, foreshadowing its eventual decline. King Albert of Sweden conceded Gotland to the allied Teutonic Order as a pledge (similar to a fiefdom). An invasion army under Konrad von Jungingen (1355–1407), the Grand Master of the Order, conquered the island in 1398, destroying Visby and driving the Victual Brothers out of Gotland.