Following the 1939 Soviet invasion of Poland, resulting in the partition of Polish territory between Nazi Germany and the Soviet Union (USSR), Jewish communities in eastern Poland welcomed with some relief the Soviet occupation, which they saw as a "lesser of two evils" than openly antisemitic Nazi Germany. The image of Jews among the Belorussian and Ukrainian minorities waving red flags to welcome Soviet troops had great symbolic meaning in Polish memory of the period. Jan T. Gross noted that "there were proportionately more communist sympathizers among Jews than among any other nationality in the local population". In the days and weeks following the events of September 1939, the Soviets engaged in a harsh policy of Sovietization. Polish schools and other institutions were closed, Poles were dismissed from jobs of authority, often arrested and deported, and replaced with non-Polish personnel. At the same time, 100,000 Jewish Poles fought to defend Poland against the Nazi-Soviet invasion, while at least 434 Polish Jews who had been awarded officer rank by the Polish Army were murdered by the Soviets in the Katyn Massacre because of their loyalty to Poland.