A member of a military and religious order whose full title was the Order of the Knights of the Hospital of St Mary of the Teutons in Jerusalem. Founded in 1190 at Acre, it was made up of knights, priests, and lay brothers and was active in Palestine and Syria, though its members retreated to Venice when the Crusaders failed to contain the Muslims. The Holy Roman Emperor Frederick II employed the order as missionaries to overcome and convert the pagans beyond the north‐eastern border of the empire and in this they were very successful, gaining Prussia in 1229.

In 1234, though in practice independent, they declared that they held the lands they had conquered as a fief from the pope. Joining with the Livonian Order, they continued to advance around the Baltic coast, amassing huge territories, but their progress was checked decisively when they were defeated at Tannenberg in 1410 by King Ladislas of Poland. In 1525 the Grand Master, Albert of Brandenburg, became a Lutheran, resigned his office, and the order was declared secular, and it remained an order under the control of the Electors of Brandenburg.