Teutonic takeover of Danzig (Gdańsk) participant Margraviate of Brandenburg
Under Swietopelk II, Gdańsk became an important trading site on the lower Vistula.The Margraviate of Brandenburg entered the scene after Mestwin II, son of Swietopolk, concluded the Treaty of Arnswalde with them, in order to receive aid against his brother, Wartislaw. The margraves took over the town in 1270/1 from Wartislaw, but did not hand it over to Mestwin until the latter was able to force them out by concluding an alliance with Boleslaw Pobozny, duke of Greater Poland. Under the rule of Brandenburg, conflicts erupted between the Slavic and German populations, which cost many lives. In the 1282 Treaty of Kępno Mestwin II promised his Pomerelian duchy to his ally Przemysł II, duke and later king of Poland, who succeeded to the duchy after Mestwin's death in 1294.The Margraves of Brandenburg also claimed the region and had Przemysł assassinated in early 1296. Władysław I the Elbow-high (Łokietek), Przemysł's successor, was only in loose control of Pomerelia and Gdańsk with the actual control of the area being in the hands of the local Swienca family who had come into power already under Mestwin II. In 1301, one year after Wenceslaus II of Bohemia had been crowned king of Poland, the princes of Rügen, who also claimed to be the heirs of Pomerelia, mounted an expedition. Wenceslaus, who with the Polish crown had also acquired the claim to Pomerelia, called the Teutonic Order for help. The Teutonic knights occupied Gdańsk, repelled the princes of Rügen, and left the town in 1302. While the Norwegian king Haakon backed Rügen's claims, his 1302 call to the Hanseatic cities for aid remained without answer.Wenceslaus II died in 1305 and was succeeded by Wenceslaus III, murdered in 1306. In a treaty of 8 August 1305, the margraves of Brandenburg promised to Wenceslaus III the Meissen (Miśnia) territory in exchange for Pomerelia, but that treaty was never finalized. The Teutonic Order had inherited Gniew (Mewe) from Sambor II, thus gaining a foothold on the left bank of the Vistula. Brandenburg occupied the west of the duchy after neutralizing another claimant to the area, the Cammin bishop, by burning down his see.Rebellion of 1308 and Brandenburgian siege
Meanwhile, Władysław I the Elbow-high had reestablished his power in Poland, but was occupied in the south of his realm. He appointed Bogusza as his Pomerelian governor in Gdańsk. In the summer of 1308, a rebellion was incited by the local Swienca family allied with Waldemar of Brandenburg, resulting in a Brandenburgian intervention which unseated the forces loyal to Łokietek, who later would become King of Poland. Bogusza and his men had retreated to the castle next to the town, and were besieged by the margraves.Bogusza, on the advice of the Dominican prior Wilhelm, appealed to the Teutonic Knights in Prussia for assistance.