Polish Operation of the NKVD
The Polish Operation of the NKVD in 1937–1938 was an anti-Polish mass-ethnic cleansing operation of the NKVD carried out in the Soviet Union against Poles during the period of the Great Purge. Wikipedia
Start date: 1937
Location: Soviet Union
Deaths: +/− 111,091
Perpetrators: Nikolai Yezhov (NKVD), Joseph Stalin
Target: Poles
Victims: 22% of the Polish population of the Soviet Union was "sentenced" by the operation (140,000 people)