June 22, 1941
Nazi Germany invades the Soviet Union in "Operation Barbarossa."
In accordance with previous agreements between SS and police and Wehrmacht representatives, German mobile units of Security Police and SD officials, called Einsatzgruppen, followed the frontline troops into the Soviet Union. RSHA chief Heydrich had tasked the Einsatzgruppen commanders with identifying, concentrating, and killing Jews, Soviet officials and other persons deemed potentially hostile to German rule in the east. Einsatzgruppen squads began to carry out mass shootings during the last week of June 1941.