The construction of the castle of Stegeborg was around 1220 in timber, then rebuilt in brick by 1245, despite this being a relatively peaceful period. On the death of King Valdemar II in 1241, a dispute arose over the succession, which led to the island being raided by Lubeckers who took the part of one of the claimants, Knud Duke of Blekinge who was imprisoned by his brother Erik Plovpenning (king 1241-1250) in Stegeborg. The Lubeckers conquered Copenhagen, then Stege to release the Duke. These raids continued intermittently into the 16th century. The succession wars also led to further raids in 1260 when the island was seized by Prince Järmer of Rügen. The Germans gained rights to establish a trading outpost at Brøndhøj. A Norwegian, Alf Ellingsen, was also attracted by the island, defeating a defending fleet of 30 vessels to raid Møn and other islands during the reign of Erik Glipping (1259–1286). Glipping granted Stege a town charter, granting it sole rights to trade and tax certain commodities, which existed until 1857.