1937 mass execution of Belarusians
In October 1937, there was a mass extermination of Belarusian writers, artists and statespeople by the Soviet Union occupying authorities. This event marked the peak of the Great Purge and repressions of Belarusians in the Soviet-controlled area of eastern Belarus.
Source: Wikipedia — 1937 mass execution of Belarusians (CC BY-SA 4.0)