After Poland regained independence after World War I in 1918, the Polish population made efforts to reintegrate the town with Poland. In January 1919, the Germans sent a unit of 120 soldiers to the town to prevent the outbreak of a Polish uprising. Local activist Tomasz Rogala, who co-founded a secret Polish independence organization, went to the peace conference in Versailles, where he demanded to include the town in reborn Poland. Kościerzyna was finally reintegrated with the Second Polish Republic in January 1920. The construction of the Polish Coal Trunk-Line in the interbellum contributed to the prosperity of Kościerzyna, as the town gained a modern railway connection with Gdynia, Bydgoszcz and Upper Silesia.
