Chełmża [ˈxɛu̯mʐa] (German: Kulmsee,[2] earlier Culmsee), is a town in northern Poland, in the Toruń County, Kuyavian-Pomeranian Voivodeship.

The first signs of settlement date to 10,000 BC when reindeer hunters made their visits to the area.

In 1251 (before July 22) Bishop Heidenreich bestowed city rights to Łoza and renamed it Culmsee (Kulmsee).

Later, in 1255 the four dioceses of Prussia, including the Bishopric of Culm were put under the jurisdiction of the Archbishopric of Riga as metropolitan[citation needed].

[8] In the 14th century, papal verdicts ordered the restoration of the territory to Poland, however, the Teutonic Knights did not comply and continued to occupy it.

[8] After Riga's dissolution in 1566 the bishops of Chełmno attended the councils of the ecclesiastical province of the metropolitan of Gniezno.

In 1621 and 1627 the town hosted the court of Polish King Sigismund III Vasa along with Prince Władysław.

The constant warfare led to the fall of the city, and its breaking point was reached due a plague that happened in years 1708–1710.

Poles rose up against Germanisation and protests were made against forced teaching in schools in German language.

[5] In November 1918 Poland regained independence, and on 8 January 1919 local Poles attacked a Grenzschutz unit but were repelled.

In revenge the Germans shelled the town by artillery, and seven civilians, including two boys aged 8 and 12, were killed.

National Democrats and at the second place socialists led by Stanisław Nehring became the main parties in Chełmża.

After the joint German-Soviet invasion of Poland, which started World War II in September 1939, the town was occupied by Germany, which carried out a genocidal campaign against the local Polish and Jewish population.

[13] The German state at the time considered Poles and Jews to be untermenschen and planned their eradication as national groups.

In early 1945, in Chełmża, Polish forced labourers evacuated from Jajkowo were forcibly conscripted by the Germans to the Organisation Todt, however, some managed to escape.

The losses inflicted by German occupation regarding the population were gradually reversed and in 1980 Chełmża counted 15,000 inhabitants.