was an influx of Jews, who, however, gradually emigrated westwards in the 19th century. Sępólno was part of the short-lived Polish Duchy of Warsaw in 1807–1815 during the Napoleonic Wars, and afterwards it was re-annexed by Prussia. The Evangelical church was built in 1857-1858 and has since been demolished. In the 19th century, Jews were obliged to give 30 Tympf, nine veal roasts, six beef roasts, six pounds of tallow, and one pound of gunpowder to the Catholic parish every year on Corpus Christi and Easter. In 1871, the town became part the German Empire. Zempelburg formed part of the Flatow district of the province of West Prussia. It was a center for the textile and shoemaking industries. Despite Germanisation policies, Poles established various organisations, including the Bank Ludowy ("People's Bank") in 1910. Until 1919, Zempelburg belonged to the district of Flatow in the administrative district of Marienwerder in the province of West Prussia of the German Reich. The city had 3818 inhabitants in 1910, of which 637 were Poles. In terms of religion, in 1905 there were 57.0% Protestants, 32.7% Catholics and 10.3% Jews. After the First World War, Zempelburg had to be ceded to Poland without a referendum due to the provisions of the Versailles Treaty in 1920 for the purpose of establishing the Polish Corridor. It was incorporated into the new Pomeranian Voivodeship. The German-speaking residents of Zempelburg became the ethnic minority of German Poles. Zempelburg received the Polish name Sępólno Krajeńskie. At that time, the town was the district seat of the Sępoleński Powiats. In 1920, the eastern part of the former Flatow district with the towns of Kamień Krajeński, Więcbork and Sępólno was reintegrated with the restored Polish Republic after the Treaty of Versailles. The town became the seat of Sępólno County. World War II Sępólno was invaded by Nazi Germany on September 1, 1939, the first day of World War II, and was later annexed and made the seat of Zempelburg district within the Reichsgau Danzig-West Prussia. During the German occupation, Poles were subject to persecutions, mass arrests, Germanisation, expulsions and massacres. Numerous Poles were imprisoned in a concentration camp in Radzim and in a prison established by the Selbstschutz in Sępólno, and later murdered on site or deported to other Nazi concentration camps. Mass arrests of Poles were carried out from September 1939, and the first executions of Polish inhabitants were carried out