The first of the Polish princes to recognized the danger was Swietopelk of Gdansk, in 1242. The Knights wanted to take from him both banks of the Nogat branch of the Vistula. Swietopelk closed the Vistula to the Germans and attacked them, calling at the same time for a rising in Prussia, which soon broke out. The war lasted six years -- Swietopelk had against him the Order, Conrad of Masovia, Boleslaw the Pious (prince of Wielkopolska), two of his own brothers and the pope, who proclaimed a crusade against Prussia. A peace treaty was signed in 1248 and Swietopelk had to yield the territories on the right bank of the Vistula.
In 1304 Wladyslaw Lokietek of the Piasts returned from exile to restore the Polish monarchy and reunite the fragments of the state dissolved by the death of its last king in 1138. He was recognized in 1306 in Little Poland and Pomerania; Great Poland fell to him in 1314, and in 1320 he was crowned king in Cracow.
In 1308, Pomerania's former rulers appealed to the neighboring margraves of Brandenburg for aid against King Wladyslaw who had deposed them. The troops of Margrave Waldemar invaded Pomerania and occupied it, except for the fortress of Gdansk, defended by Judge Bogusz. The city of Gdansk was taken when the German burghers opened its gates to the Brandenburg forces. Another Brandenburg army was sent against Boguslaw IV, prince of Szcecin, the King's only ally in the north. They attacked his duchy and burnt down the city of Kamien. Boguslaw IV was thus neutralized and the bishop of Kamien even joined the Margrave Waldemar in his assault against Gdansk.
Judge Bogusz defended stubbornly the castle, but his position was hopeless. The King advised him to call on the help of the Knights of the Cross as a last resort. The abbot of the Dominicans of Gdansk endorsed that advice and Bogusz, with no other alternative in sight, appealed to the Grand Master Herman von Ploetzke.
The fortified castle of Gdansk was situated in the fork of the Radun and Motlawa branches of the Vistula delta. The 'relief force' led by the komtur (governor) of Chelmno, Gunter von Schartzburg, advanced from the sea, across the coastal wetlands. The Brandenburg forces retreated to the west, holding only Slawno and Slupsk.
The Knights of the Cross first secured their hold on a portion of the castle and then displaced the Poles from the rest. They compelled Bogusz to give them written authority to remain in the castle until Lokietek reimbursed the cost of the rescue operation. On November 14th, 1308, they attacked the city, slaughtering its civilian inhabitants and burning their houses. The abbot of Oliwa, who tried to comfort the dying, was permitted to hear confessions only 'when conditions allowed it.'