The Teutonic Knights was a military and religious order that was founded in the late 12th century by German merchant crusaders. During the Third Crusade, in about 1190, German pilgrims to Palestine organized the Teutonic Knights for the defense of the roads to Palestine. They expanded their territories eastwards and supported their colonization by building fortresses as they moved. Except for some church territories, the Knight's Empire stretched from Prussia to Estonia on the Baltic coast. In 1198, the Teutonic Knights became an order of knights that was confined to Germans of noble birth. The style of the Order also became increasingly military. In 1229, the knights embarked on an extensive campaign in Prussia. After the conquest of this German territory, they transferred their headquarters from Transylvania (Rumania) to Prussia, where they became the armed vanguard of the German eastward expansion.
In West Prussia, the knights founded the cities of Elbing, Thorn, Culm, and Graudenz and they built several fortified castles. Marienburg, the Knight's most famous fortress, was situated on the river Nogat and it that was the seat of the Order's Hochmeister, or grand master. Under the protection of the Order's fortified castles, German farmers colonized the rich lands and developed the soil's potential, while the Slavic tribes were converted to Christianity.
The knights combined the dedication, discipline and organizational experience of monasticism with the military purposes of the crusade. In 1525, the last grand master Albert of Hohenzollern adopted Lutheranism and secularized the order and its territories. The German state of Brandenburg-Prussia eventually absorbed the lands, and the spirit, of these crusading knights. The order was suppressed by Napoleon in 1809, but it was revived in Austria in 1840. The Knights of the Teutonic Order became a mendicant order in 1929.