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. (February 2011)
The Prussian Confederation (German: Preußischer Bund, Polish: Związek Pruski) was an organization formed on 21 February 1440 at Marienwerder by a group of 53 nobles and clergy and 19 cities in Prussia, to oppose the arbitrariness of the Teutonic Knights. It was based on the basis of an earlier similar organization, the Lizard Union established in 1397 by Chełmno Land nobles.
In 1454, the leader of the Confederation, Johannes von Baysen (Jan Bażyński), formally asked King Casimir IV Jagiellon, to incorporate Prussia into the Kingdom of Poland as a fief. This marked the beginning of the Thirteen Years' War between the Order's State and Poland, with the Prussian cities financing the military costs of the latter.
According to the 1411 First Peace of Thorn which followed the Teutonic Knights' defeat in the Battle of Grunwald, the Teutonic Order had to pay high reparations to the Kingdom of Poland. The monastic state imposed high taxes on the cities to raise the funds as well as to re-arm for another war against Poland. In the 1420s, Grand Master Paul von Rusdorf brought stability to the Order and its relations, but fighting with Poland resumed in 1431, when the Knight's invasion into Poland during the Lithuanian Civil War sparked another Polish-Teutonic conflict.