Editing Duchy of Prussia (section)

== Overview ==
The duchy became the first [[Protestant]] state when [[Albert, Duke of Prussia]] formally adopted [[Lutheranism]] in 1525. It was inhabited by a German, Polish (mainly in [[Masuria]]), and Lithuanian-speaking (mainly in [[Lithuania Minor]]) population.<ref>{{cite book |url=https://books.google.com/books?id=wu5AAQAAMAAJ&pg=PA284 |title=Notes and Queries |publisher=[[Oxford University Press]] |year=1850 }}</ref>

In 1525, during the [[Protestant Reformation]], in accordance to the [[Treaty of Kraków]], the [[Grand Masters of the Teutonic Knights|Grand Master]] of the [[Teutonic Knights]], Albert, [[secularization|secularized]] the order's prevailing Prussian territory (the Monastic Prussia), becoming [[Albert, Duke of Prussia]]. As the region had been a part of the [[Kingdom of Poland (1385–1569)|Kingdom of Poland]] since the [[Second Peace of Thorn (1466)]],<ref>{{Cite book |last=Górski |first=Karol |title=Związek Pruski i poddanie się Prus Polsce: zbiór tekstów źródłowych |year=1949 |publisher=Instytut Zachodni |location=[[Poznań]] |language=pl,la |pages=96–97, 214–215 }}</ref> King of Poland [[Sigismund I the Old]], as its suzerain, granted the territory as a hereditary [[fief]] of Poland to Duke Albert per the Treaty of Kraków, a decision that was sealed by the [[Prussian Homage]] in [[Kraków]] in April 1525. The new duke established Lutheranism as the first Protestant [[state church]]. The capital remained in [[Königsberg]] (modern [[Kaliningrad]]).

The duchy was inherited by the [[House of Hohenzollern|Hohenzollern]] [[prince-elector]]s of [[Margraviate of Brandenburg|Brandenburg]] in 1618. This [[personal union]] is referred to as [[Brandenburg-Prussia]]. [[Frederick William, Elector of Brandenburg|Frederick William]], the "Great Elector" of Brandenburg, achieved full sovereignty over the duchy under the 1657 [[Treaty of Wehlau]], confirmed in the 1660 [[Treaty of Oliva]]. In the following years, attempts were made to return to Polish suzerainty, especially by the capital city of Königsberg, whose burghers rejected the treaties and viewed the region as part of Poland.<ref name=JJ/><ref>{{Cite web | url=http://bazhum.muzhp.pl/media//files/Komunikaty_Mazursko_Warminskie/Komunikaty_Mazursko_Warminskie-r1995-t-n3/Komunikaty_Mazursko_Warminskie-r1995-t-n3-s311-313/Komunikaty_Mazursko_Warminskie-r1995-t-n3-s311-313.pdf | title="Historia Królewca. Szkice z XIII-XX stulecia", Janusz Jasiński, Olsztyn 1994 : [recenzja] | language=pl | trans-title="History of Königsberg. Sketches from the 13th to the 20th centuries", Janusz Jasiński, Olsztyn 1994: [review] | author=Andrzej Kamieński }}</ref> The Duchy of Prussia was elevated to a [[Kingdom of Prussia|kingdom]] in 1701.