In the Spring of 1941 Four Einsatzgruppen were organised who together numbered some 3000 people. They were mobile units of the SD and the Security Police who were disposed after the combat forces to take control of the areas that the army had occupied. Each unit advanced in a predetermined direction toward a pre-assigned sector. The Einstazgruppen engaged in "special tasks", ie: mass murder on an unprecedented scale. Their orders were spelled out in a letter given to them on July 2 by Heydrich:
'The following is the gist of the highly important orders that I have issued to the Einsatzkommandos...Executions: The following categories are to be executed: Comintern officials (as well as all professional Communist politicians); party officials of all levels; and members of the central, provincial, and district committees; people's commissars; Jews in the party and state apparatus; and other extremist elements (saboteurs, propagandists, snipers, assassins, agitators, etc.).'
In Nazi eyes, all Jews were Bolsheviks, extremists, and dangerous. Hence practically speaking, the order encompassed all Jews.
We know that these Einsatzgruppen were helped by other units who participated in the murder, such as Polish Battalions, other SS units, the Wermacht, and other local militias.
By the Spring of 1943, when the Germans began their retreat from Soviet Territory, the Einsatzgruppen had murdered approximately 1.25 million Jews and hundreds of thousands of other Soviet nationals including Prisoners of War.
