September 17, 1939, is a significant and controversial date for Belarusians. On this day, the USSR attacked Poland, which resulted in the unification of Belarus. However, this event also led to Soviet repressions in the western part of the country. Although the Soviet Union never celebrated the date as a holiday, independent Belarus made it an official holiday five years ago. Belsat has examined what state propaganda is emphasizing this year and why it is important to discuss.