 In 1454, the Prussian Confederation, an alliance of Prussian cities and nobility opposed to the increasingly oppressive rule of the Teutonic Knights, asked King Casimir to take over Prussia and initiated an armed uprising against the Knights.Casimir declared a war on the Order and the formal incorporation of Prussia into the Polish Crown; those events led to the Thirteen Years' War of 1454–66.The mobilization of the Polish forces (the pospolite ruszenie) was weak at first, since the szlachta would not cooperate without concessions from Casimir that were formalized in the Statutes of Nieszawa promulgated in 1454.