During the Revolution and the civil war, Russia lost many of its western provinces. Estonia, Latvia, Lithuania, and Finland each declared independence in 1917–1918, whereas Poland and Romania took advantage of the turmoil in Russia to appropriate adjacent territories. When Hitler offered the Soviet Union a nonaggression pact in August 1939, Stalin sensed an opportunity to return these lands. On 23 August, Germany and the Soviet Union concluded a pact that divided eastern Europe between them, and a week later, Germany attacked Poland, thus triggering World War II. After the Polish Army virtually disintegrated, Germans surrounded Warsaw and reached the demarcation line set by the Nazi-Soviet pact, the USSR invaded Poland from the east on 17 September. By July 1940, it absorbed most of the former imperial possessions. This chapter analyzes the rural societies of eastern Poland and the Baltic States in the interwar period, outlining the strains they experienced and discussing how the Soviet government attempted to exploit those strains after it occupied those regions. Soviet reforms found some support among borderland people but did not take root before the German attack and the repressions provoked the growth of anti-Communist resistance.