fighting the heathen Prussians. But although the Knights operated mainly in Prussia, their general headquarters still continued at Acre, until the latter fell in 1291, after which they transferred to Venice. Finally, in 1309, the seat of the order was established in the famous fortress of Marienburg in Prussia.[20] In 1236 the Teutonic Order absorbed the remnants of the Brothers of the Sword, an order of knighthood which had been founded some thirty-four years earlier for the purpose of subjugating and christianizing the peoples of the Baltic countries of Livonia, Lettonia and Esthonia (now known as Latvia, Lithuania and Estonia). Thus the Teutonic Knights prevailed in these countries. By donations and conquest the knights gradually increased their holdings, until they included large parts of Prussia, Kurland and Lithuania. Although these followers of Christ used the unorthodox methods of fire and sword for the propagation of the faith, it cannot be denied that they greatly contributed to the pacification and civilization of the peoples under their jurisdiction. They encouraged cultivation of the land and built a great number of towns and villages, providing each with a church. In some places they erected schools and, faithful to the original purpose of their order, they established hundreds of hospitals and hospices. In this respect it is worthy of note that the Teutonic Knights were the first to establish a mental hospital (Dollhaus) in Germany, namely at Elbig in 1316. The knights also proved to be clever businessmen inasmuch as they sponsored profitable markets in foreign countries for the produce of their land.