Clashes of arms continued until 31 January, but neither of the belligerents benefited: at the 1920 Spa Conference the division of the former duchy along the Olza was confirmed. The eastern part of Cieszyn Silesia was incorporated into the Polish Autonomous Silesian Voivodeship, while the western part (including the Zaolzie region) became part of Czechoslovakia. This was confirmed on 5 August 1920 by the Conference of Ambassadors. After World War II the remaining German population was expelled.