During the course of 19th-century industrialization, Nakło developed further after being connected with the Prussian Eastern Railway in 1851. It became part of the Prussian-led German Empire in 1871. After World War I, in 1918, Poland regained independence and many inhabitants joined the Greater Poland uprising (1918–19) in aim to reintegrate the town with the reborn state.[2] The town was captured by Polish insurgents on 1 January 1919, however, they were forced to withdraw in accordance to a Polish-German truce.[4] The Germans then brought reinforcements to the town.[4] In June 1919, American and British journalists visited the town, and the Germans tried to keep Poles away from the journalists.[4] Local Polish craftsman Antoni Nadskakuła shouted a pro-Polish and pro-Allied slogan to the journalists, and was later lynched by the Germans in revenge, and his workshop was destroyed.[4] The town was eventually restored to the Second Polish Republic according to the Treaty of Versailles. Within interwar Poland, it was administratively located in the Pomeranian Voivodeship.
During the invasion of Poland, which started World War II, the German army invaded the town on 3 September 1939, and afterwards it was occupied by Nazi Germany until January 1945.[2] The German gendarmerie and the Selbstschutz carried out mass arrests of Poles in October and November 1939, and a prison for Poles was established in the local gymnasium.[5] Many Poles from Nakło, including teachers, craftsmen, merchants and children, were murdered in large massacres in the nearby village of Paterek.[6] In November 1939, the commander of the SD-EK 16 declared that all Polish intelligentsia capable of resistance had been eliminated.[7] Many Polish families expelled by the Germans from the region were deported to Nakło and then marched from the town to the nearby Potulice concentration camp.[8] 73 Poles from the Nakło County, including 20 policemen, were also murdered by the Russians in the large Katyn massacre in April–May 1940.[9] In August 1944, the Germans brought around 300 Polish forced labourers aged 15–50 from the Wyrzysk area to the town, and then deported them to a newly established forced labour camp in Jajkowo.[10]
^Molesztak, Aldona (2020). "Doświadczenia obozowe dzieci w niemieckim obozie przesiedleńczym i pracy w Potulicach i Smukale - wspomnienia więźniarek". In Kostkiewicz, Janina (ed.). Zbrodnia bez kary... Eksterminacja i cierpienie polskich dzieci pod okupacją niemiecką (1939–1945) (in Polish). Kraków: Uniwersytet Jagielloński, Biblioteka Jagiellońska. p. 197.
^Paczoska, Alicja (2002). "Obóz robot fortyfikacyjnych w Jajkowie koło Brodnicy". Biuletyn Instytutu Pamięci Narodowej (in Polish). No. 8-9 (19-20). IPN. p. 50. ISSN1641-9561.