Bartoszyce (pronounced Barto-shitse [bartɔˈʂɨt͡sɛ] ⓘ; German: Bartenstein, [ˈbaʁtn̩ʃtaɪn] ⓘ) is a town on the Łyna River in northern Poland, with 22,597 inhabitants as of December 2021.

Around 1241 the Teutonic Knights (the monastic German Order) constructed a castle on the left shore of the Łyna River on the border between the Old Prussian regions of Natangia and Bartia.

First documented in 1326 under the name Rosenthal, it received town privileges from the Teutonic Grand Master Luther von Braunschweig in 1332.

[7] At the beginning of the subsequent Thirteen Years' War, the Teutonic castle was destroyed and was not rebuilt afterward.

After the peace treaty signed in Toruń in 1466, the town became part of Poland as a fief held by the State of the Teutonic Order.

[5] During World War II, the town was 50% destroyed in fighting between German forces and the Soviet Red Army.

After German surrender, the Soviets ceremoniously transferred sovereignty over the town to Polish authorities on June 15, 1945.

Remaining German residents who had survived were either evacuated or later expelled in accordance with the Potsdam Agreement, and the town was repopulated with Poles.

As part of the repressions against the Catholic Church, the communists created a special military unit in Bartoszyce, to which they forcibly conscripted students of theological seminaries.