September 17, 1939
Red Army Invasion of Poland
On September 17, 1939, the Red Army began its invasion of Poland, implementing the secret provisions of the Molotov-Ribbentrop Pact. The attack was launched without a declaration of war while the Polish army was fighting the Germans in the west. The Soviet aggression led to the occupation of eastern Poland, mass deportations of the population, and crimes against Polish officers and intelligentsia.
