Monastic State of the Teutonic Knights
The Monastic state of the Teutonic Knights was established by the Teutonic Knights in 1226. The German Roman Catholic religious order was founded during the siege of Acre during the Third Crusade in 1190. They moved to Transylvania to help Andrew II of Hungary against the Cumans in 1221 but they came into conflict with the Hungarian king and were forced to leave Transylvania in 1225.
The Polish Duke Konrad I of Masovia applied to the Teutonic Knights for aid against the pagan Prussians in 1226. Konrad gave them Chelmno Land (today’s central Poland bounded by the Vistula and Drweca rivers) as a base for their campaigns, while Holy Roman Emperor Frederick II and the Pope gave the Teutonic Order a special privilege for the conquest of Prussia and its occupation, including Chelmno Land. The Teutonic Knights conquered the Prussian lands over the following decades and absorbed the Livonian Brothers of the Sword, while Prussia was mostly colonized by the German emigrants after they suppressed the revolts of the Slavic population.
Military campaigns of the Teutonic Knights against the pagans lasted until the 14th century when they came into conflict with Lithuania, while the seizure of Pomerania from Brandenburg in 1308/1309 provoked a conflict with Poland. The Monastic State of the Teutonic Knights evolved into an important North European and reached its zenith under the Grand Master Winrich von Kniprode (1351-1382). However, the Teutonic Knights were severely defeated by the Poles and Lithuanians in the Battle of Grunwald (Tannenberg) in 1410 and never recovered from the defeat. They were forced to cede West Prussia and Pomerelia to Poland with the second Treaty of Torun in 1466, while the remaining East Prussia became a Polish fief. The rule of the Teutonic Knights in Prussia finally collapsed in 1525 when the Grand Master Albert of Brandenburg accepted Protestantism, dissolved the order and declared Prussia a secular duchy under Polish suzerainty.