Polish–Teutonic War (1519–1521)

The Polish–Teutonic War of 1519–1521, also known as the Last War, was the final major conflict between the Kingdom of Poland and the Teutonic Order. It stemmed from the continuing refusal of the Teutonic Order, led by Grand Master Albert of Brandenburg-Ansbach, to acknowledge Polish sovereignty over Prussia, as mandated by the Second Peace of Thorn in 1466, which had effectively turned the Order's Prussian territory into a Polish fief.

The war was initiated by Albert of Brandenburg-Ansbach, who sought to break free from Polish vassalage. He secured support from Emperor Maximilian I and other Holy Roman Empire princes. In response, Polish King Sigismund I the Old, allied with his nephew Duke Albert of Prussia, the future Duke Albert I.

The conflict was characterized by raiding and sieges rather than large-scale pitched battles. Polish forces focused on capturing key Teutonic strongholds in Prussia. Notable sieges included those of Allenstein (Olsztyn) and Marienburg (Malbork). The war was marked by widespread devastation and economic hardship in both Poland and Prussia.

After two years of fighting, neither side had achieved a decisive victory. The conflict ended with the Treaty of Thorn (1521), mediated by Charles V, Holy Roman Emperor. While the treaty reaffirmed the terms of the Second Peace of Thorn, it also brokered a four-year truce. Ultimately, this truce led to the secularization of the Teutonic Order in Prussia. In 1525, Albert converted to Lutheranism and secularized the Order, becoming the first Duke of Prussia, a vassal of Poland. This event marked the end of the Teutonic Order as a significant military and political power and ushered in a new era in the history of Prussia and the Baltic region.