The 14th century marked the apogee of the power of the Teutonic Order in eastern Europe. The Knights began the penetration of Poland, where Germans settled some 650 districts and where the middle class in the towns became German in speech and law, much to the alarm of the rulers and nobles. In the same period, the Knights advanced into Lithuania, a huge region extending from the Baltic to the Black Sea, the last pagan area in Europe. German colonization and town building first opened and civilized this region.
The first Polish war, marking a sharp reaction to German penetration and putting the order for the first time on the defensive. With the aid of John of Bohemia, Louis of Hungary, Albert of Austria, Louis of Brandenburg, and others, the order emerged triumphant, and the Poles were obliged to conclude a truce.
Peace of Kalisz. The Poles, despite papal support of their claims to Pomerelia, were obliged to recognize the order's possession of the territory, in return for a promise of aid against the Lithuanians. Poland was thus cut off from the Baltic.
The Prussian Revolt, a great uprising against the oppressive rule of the order, in which the Prussian nobility and towns took part. The movement was supported by the Poles, and Casimir of Poland declared war on the order.
Second Peace of Thorn: Prussia was divided: (1) West Prussia (including Danzig, Kulm, Marienwerder, Thorn, and Ermeland) went to Poland, thus cutting East Prussia off from the rest of Germany and securing for Poland access to the sea; (2) East Prussia was retained by the order, with Königsberg as the capital. East Prussia, Brandenburg, and Memel (today Klaipeda in Lithuania) were all to be held as Polish fiefs. The order was opened to Polish members. This peace marked the definitive end of the German advance until the partitions of Poland.
The decline of the Teutonic Order continued (growing commercialization, exclusiveness, lack of new blood, loss of discipline, Slavic pressure), despite efforts at reform.
East Prussia was finally secularized by the grand master, Albrecht (Hohenzollern) of Brandenburg, and became a fief of the Hohenzollerns under the Polish crown.
The order itself survived in Germany until 1809 and was later revived in 1840 under Habsburg auspices, with its original functions (e.g., ambulance service in war).
