Sępólno Krajeńskie () is a town in northern Poland, in the Kuyavian-Pomeranian Voivodeship. It is the capital of Sępólno County (Powiat Sępoleński) and Gmina Sępólno Krajeńskie. Zempelburg was part of Greater Poland until 1772. From 1772 to 1807, it belonged to Prussia. From 1807 to 1815, it was part of the Duchy of Warsaw. The city was recaptured by Prussia and became part of West Prussia from 1815 to 1920. In 2016, it had a total population of 15,907 with an urban population of 9,258 and rural population of 6,649. Location The city is located in the historical Krajna forest on a high bank of the Sępólna River. It is located 63 km northwest of Bydgoszcz (Bromberg). History The town formed part of the Kalisz Voivodeship of the Greater Poland Province of the Polish Crown from 1314-1793. The town received Magdeburg rights in 1360 from King Casimir the Great of Poland. The Catholic church, mentioned as early as 1360, suggests that it was located in the Sępólna River valley. According to legend, the castle manor was lost when the river and nearby Dziechowo lake flooded. Sępólno was founded as a private town. It initially belonged to the Pakoski family. Later, it was owned by the Ostroróg, Goślubski, Zebrzydowski, Smoszewski, Brez and Potulicki families until 1821. During the Thirteen Years' War between Poland and the Teutonic Knights the area was captured by the Knights and the town was looted. Sępólno suffered during the Swedish invasions and epidemics of the 17th century. The Evangelical church on Schulenberg was destroyed in 1620. The location of a castle mentioned in 1679 is unknown. In 1764, the Niederstadt had 79 houses and the suburbs 71. In the 18th century, the town had a number of weavers, shoemakers and farmers. In 1773 Zempelburg had 70 craftsmen, including eight cloth makers and numerous shoemakers. A new synagogue was built in 1734. The Jews of the town traded textiles and other fabricated goods to both Royal Prussia and Duchy of Prussia. The Jewish community in Zempelburg was still active until the early 20th century. The town was annexed by the Kingdom of Prussia during the First Partition of Poland in 1772. Fires in 1781 and 1782 destroyed 73 houses, so that there existed now 84 devastated sites in the town. In the year of 1783 the town had altogether 183 houses, most of them having thatched roofs. There