The Teutonic Order is a Catholic religious institution founded as a military society c. Its members have commonly been known as the Teutonic Knights , having historically served as a crusading military order for supporting Catholic rule in the Holy Land and the Northern Crusades during the Middle Ages , as well as supplying military protection for Catholics in Eastern Europe. Purely religious since , the Teutonic Order still confers limited honorary knighthoods. Thus the term "Teutonic" echoes the German origins of the order Theutonicorum in its Latin name.
After the capture of Acre they took over a hospital in the city in order to take care of the sick and began to describe themselves as the Hospital of St. Mary of the German House in Jerusalem. After Christian forces were defeated in the Middle East, the Order moved to Burzenland southeastern Transylvania in 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 , after attempting to build their own state within Transylvania and Pope Honorius III's papal bull claiming authority over the Order's territory in Transylvania and its tax exemption toward the king. Starting from there, the Order created the independent State of the Teutonic Order , adding continuously the conquered Prussians' territory, and subsequently conquered Livonia. 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 , a Polish-Lithuanian army decisively defeated the Order and broke its military power at the Battle of Grunwald. However, the Knights successfully defended their capital in the following Siege of Marienburg Malbork and the Order was saved from collapse.
