When the Communists invaded Poland, they massacred many thousands of Poles.

The number of victims is estimated at about 22,000.[1] The victims were executed in the Katyn Forest in Russia, the Kalinin and Kharkiv prisons, and elsewhere. Of the total killed, about 8,000 were officers taken prisoner during the 1939 Soviet invasion of Poland, another 6,000 were police officers, and the rest were arrested Polish intelligentsia that the Soviets deemed to be "intelligence agents, gendarmes, landowners, saboteurs, factory owners, lawyers, officials and priests"