This thesis is based on German, Soviet, American, and British primary source material, as well as memoirs and a variety of secondary sources. Through an investigation of the Polish-Lithuanian dispute, the Polish-Soviet War, the Baltic attempts to achieve independence, as well as German and Soviet military manoeuvres in the Baltic region, far reaching and active cooperation, previously largely unnoticed, has been revealed. The research demonstrates that Germany and Soviet Russia, between the years 1918 and 1920, cooperated extensively in order to prevent Poland from exerting domination over the Baltic States and in attempting to prevent effective cooperation among the Baltic States.