Soviet invasion of Poland

The Soviet invasion of Poland occurred in September 1939, when the Soviet Union, under Stalin, jointly invaded eastern Poland shortly after Nazi Germany attacked from the west. This was part of the secret protocols of the Molotov-Ribbentrop Pact, a non-aggression treaty between the USSR and Germany, which divided Eastern Europe into spheres of influence. The invasion resulted in the Soviet occupation of eastern Poland, leading to arrests, executions, and forced relocations of thousands of Poles. It marked the beginning of Soviet dominance over eastern Poland and significantly contributed to the outbreak of World War II in Europe.