Although the SS-Einsatzgruppen had been deployed in previous military campaigns, they operated during the invasion of the Soviet Union in June 1941 for the first time officially under the title ‘Einsatzgruppen of the Security Police and the SD’. Three of the Einsatzgruppen, A to C, were assigned to each of the three Army Groups, North (for the Baltic), Centre (for Belarus) and South (for northern and central Ukraine), whilst the fourth – Einsatzgruppe D – was assigned to the German 11th Army, which was set to advance together with the two Romanian armies through southern Ukraine, the Crimea and the Caucasus. Einsatzgruppe (EG) B, with an initial strength of 655 men, was assigned to Army Group Centre (see Figure 13). In accordance with the agreement reached between the High Command of the Army (Oberkommando des Heeres, or OKH) and the RSHA in the spring, its two Sonderkommandos (SK), 7a and 7b, would operate in the army rear areas (rückwärtige Armeegebiete), where they would be responsible for securing specific materials and card indexes as well as important individuals (‘leading emigrants, saboteurs, terrorists etc.’), whilst its two larger Einsatzkommandos (EK), 8 and 9, would be deployed further back in the army group rear areas (rückwärtige Heeresgebiete), where they would investigate and tackle movements hostile to Germany – to the extent that these movements did not constitute part of the enemy's armed forces – and provide information to the Wehrmacht on political developments. An Advance Commando Moscow (Vorkommando Moskau), which was to fulfil special tasks in the Soviet capital, was also part of EG B.

At the time of its departure from Pretzsch, Einsatzkommando 9 contained a total of 144 people. Of these, fifteen were SS officers. A further eighty-three were officials of non-officer rank in the Gestapo, the Criminal Police, the SD or the Waffen SS, of which fifty-one were non-commissioned officers (NCOs). As many as forty-six drivers and baggage personnel also belonged to the commando. This contingent included a platoon of Waffen SS reservists. A platoon of the Order Police (Ordnungspolizei) – the 3rd platoon of the 2nd company of Reserve Police Battalion 9 – also joined the commando in Warsaw. This platoon totalled forty-two men, of which fourteen were NCOs and twenty-eight from the rank and file. The addition of the police platoon took the strength of EK 9 to a combined total of 186 men.