After World War I and the resolutions of the 1919 Treaty of Versailles, the Province of Brandenburg shifted to the eastern edge of the German Weimar Republic, sharing a long common border with the Second Polish Republic. In 1920, the Greater Berlin Act expanded the borders of Berlin, incorporating numerous surrounding districts and towns from Brandenburg to form Greater Berlin ("Groß-Berlin") with a population of about 2,000,000, including the former town of Charlottenburg, the seat of Brandenburg's provincial government. The Great Depression helped the Nazi Party to establish itself as an important political power. After the "Machtergreifung" on 30 January 1933, the Nazi "Gauleiter" Wilhelm Kube held the office of the "Oberpräsident", succeeded by Emil Stürtz in 1936. Due to its location in the vicinity of the German capital, Brandenburg was a centre of the Nazi terror regime, with concentration camps like Sachsenhausen and Ravensbrück and Nazi residences like Karinhall. In the late days of World War II it was the site of the bloody encounters of the Seelow Heights, at Halbe and finally the Battle of Berlin.