 Upon the 1815 Vienna Congress, Osiecko belonged to "Kreis Birnbaum" in the Prussian Grand Duchy of Posen, from 1887 to "Kreis Schwerin".After World War I, "Oscht" with the Posen-West Prussia frontier region remained with the German Weimar Republic according to the Treaty of Versailles.Osiecko returned to the Republic of Poland after World War II as stipulated by the Allied Potsdam Agreement and the German population was expelled.