Following the Soviet invasion of Poland at the onset of World War II in accordance with the Nazi-Soviet Pact against Poland, the Soviet Union acquired over half of the territory of the Second Polish Republic or about 201,000 square kilometres (78,000 sq mi) inhabited by over 13,200,000 people. Within months, in order to de-Polonize annexed lands, the Soviet NKVD rounded up and deported between 320,000 and 1 million Polish nationals to the eastern parts of the USSR, the Urals, and Siberia. There were four waves of deportations of entire families with children, women and elderly aboard freight trains from 1940 until 1941. The second wave of deportations by the Soviet occupational forces across the Kresy macroregion, affected 300,000 to 330,000 Poles, sent primarily to Kazakhstan. Thanks to a