Why were communist governments established in most nations of eastern Europe so quickly after World War 2?

Communist governments were established quickly in Eastern Europe after World War II largely due to the power vacuum left by the defeat of Nazi Germany and the influence of the Soviet Union. The USSR sought to expand its sphere of influence by supporting communist parties in these nations, often through military presence and political pressure. Additionally, the social and economic chaos following the war made many people receptive to communist ideologies that promised stability and reform. As a result, communist regimes were installed in several countries with the support or coercion of the Soviet Union.