III approved it and the Order started to play an important role in the Outremer (the general name for the Crusader states), controlling the port tolls of Acre. After Christian forces were defeated in the Middle East, the order moved to Transylvania in 1211 to help defend the south-eastern borders of the Kingdom of Hungary against the Cumans. The Knights were expelled by force of arms by King Andrew II of Hungary in 1225, after attempting to build their own state within Transylvania and Pope Honorius III's papal bull claiming the Order's territory in Transylvania. In 1230, following the Golden Bull of Rimini, Grand Master Hermann von Salza and Duke Konrad I of Masovia launched the Prussian Crusade, a joint invasion of Prussia intended to Christianize the Baltic Old Prussians. The Knights had quickly taken steps against their Polish hosts and with the Holy Roman Emperor's support, had changed the status of Chełmno Land (also Ziemia Chełmińska or Kulmerland), where they were invited by the Polish Duke, into their own property. Starting from there, the Order created the independent Monastic State of the Teutonic Knights, adding continuously the conquered Prussians' territory, and subsequently conquered Livonia. Over time, the kings of Poland denounced the Order for expropriating their lands, specifically Chełmno Land and later the Polish lands of Pomerelia (also Pomorze Gdańskie or Pomerania), Kuyavia, and Dobrzyń Land. The order theoretically lost its main purpose in Europe with the Christianization of Lithuania. However, it initiated numerous campaigns against its Christian neighbours, the Kingdom of Poland, the Grand Duchy of Lithuania, and the Novgorod Republic (after assimilating the Livonian Order). The Teutonic Knights had a strong economic base which enabled them to hire mercenaries from throughout Europe to augment their feudal levies, and they also became a naval power in the Baltic Sea. In 1410, a Polish-Lithuanian army decisively defeated the Order and broke its military power at the Battle of Grunwald. However, the capital of the Teutonic Knights was successfully defended in the following Siege of Marienburg (Malbork) and the Order was saved from collapse. In 1515, Holy Roman Emperor Maximilian I made a marriage alliance with Sigismund I of Poland-Lithuania. Thereafter, the empire did not support the Order against Poland. In 1525, Grand Master Albert of Brandenburg resigned and converted to Lutheranism, becoming Duke of Prussia as a vassal of Poland. Soon after, the Order lost Livonia and its holdings