Nidzica (Polish: [ɲiˈd͡ʑit͡sa]; formerly Nibork; German: Neidenburg [ˈnaɪdn̩bʊʁk] ⓘ; Prussian: Nīdaspils) is a town in the Warmian-Masurian Voivodeship of Poland, lying between Olsztyn and Mława, in Masuria.

[3] From 1444 Neidenburg was a member of the Prussian Confederation, at which request in 1454 Polish King Casimir IV Jagiellon signed the act of incorporation of the region to the Kingdom of Poland.

[3] The incorporation of Nidzica to Poland was confirmed in the peace treaty signed in Toruń in 1466,[citation needed] but two years later the town came under Teutonic rule, remaining under Polish suzerainty as a fief.

[6] In 1832 Polish soldiers from failed uprising against Russia were interned in the city[10] Since 1840 the local German authorities issued decrees ordering to report any Poles fleeing from the Russian Partition of Poland.

[12] At the beginning of World War I in 1914, Neidenburg was heavily damaged by invading Imperial Russian troops; 167 residential and agricultural houses, 8 public and 58 business buildings were destroyed by artillery fire on 22 August 1914.

[14] During the Kristallnacht riots in November 1938, the synagogue was destroyed and two Jewish inhabitants, Julius Naftali and Minna Zack, were killed by Nazi SA members, while several others were injured.

Neidenburg was the seat of a district in East Prussia until 1945; in that year the Red Army entered and occupied the town while pursuing the retreating Wehrmacht.

[15] In accordance to the Potsdam Agreement, Neidenburg along with the southern part of the former province of East Prussia (including most of historic Masuria) was granted to Poland, and the remaining German population was expelled.