Minsk, it reached Mogilev, which became its general headquarters, and from there Einsatzkommando 8 effected successive killings in Bobruisk, Gomel, Roslavl, and Klintsy systematically attacking the local Jewish communities, and killing the inhabitants. Meanwhile, Einsatzkommando 9 was put to work; they had left Treuburg, in eastern Prussia, and reached Vilna on 2 July. Their main theater of mass killing operations were Grodno and Bielsk-Podlaski (Biala-Podlaska). On 20 July it moved its headquarters to Vitebsk, and then exterminated the citizens of Polotzk, Nevel, Lepel, and Surazh. The command progressed to Vtasma, and from there they killed the communities of Gshatsk and Mozhaisk in the Moscow vicinity. The Soviet counter-offensive forced the Einsatzkommando to withdraw to Vitebsk on 21 December 1941. Anticipating the fall of Moscow, the Vorkommando Moskau advanced to Maloyaroslavets, earlier captured by the Wehrmacht on 18 October 1941. In practice, Sonderkommandos 7a and 7b operated behind the vanguard of the army. The actions were fast, in order to prevent the Jews from escaping the advancing German Army. To the south and east of Smolensk and Minsk, the two Sonderkommandos left a wake of dead civilians, from Velikiye Luki, Kalinin, Orsha, Gomel, Chernigov and Orel, to Kursk. Sonderkommando 7a Sonderkommando 7a led by Walter Blume, was attached to the 9th Army under General Adolf Strauß. SK 7a entered Vilna on 27 June and remained there until 3 July. Soon Vilna was in the command sphere of Einsatzgruppe A, and Sonderkommando 7a was transferred to Kreva near Minsk. The Sonderkommando was active in Vilna, Nevel, Haradok, Vitebsk, Velizh, Rzhev, Vyazma, Kalinin, and Klintsy. It executed 1344 people. SS-Standartenführer Walter Blume (June–September 1941) SS-Standartenführer Eugen Steimle (September–December 1941) SS-Hauptsturmführer Kurt Matschke (December 1941 – February 1942) SS-Obersturmbannführer Albert Rapp (February 1942–28 January 1943) SS-Sturmbannführer Helmut Looss (June 1943 – June 1944) SS-Sturmbannführer Gerhard Bast (June–October/November 1944) Sonderkommando 7b The Sonderkommando was active in Brest-Litovsk (see the Brześć Ghetto), Kobrin, Pruzhany, Slonim (the Słonim Ghetto), Baranovichi, Stowbtsy, Minsk (the Minsk Ghetto), Orsha, Klinzy, Briansk, Kursk, Tserigov, and Orel. It executed 6,788 people. SS-Sturmbannführer Günther Rausch (June 1941 – January/February 1942) SS-Obersturmbannführer Adolf Ott (February 1942 – January 1943) SS-Obersturmbannführer Josef Auinger (July 1942 – January 1943) SS-Obersturmbannführer Karl-Georg Rabe (January/February 1943 – October 1944) Sonderkommando 7c See also Vorkommando Moskau SS-Sturmbannführer Friedrich-Wilhelm Bock (June 1942) SS-Hauptsturmführer Ernst Schmücker (June 1942 – 1942) SS-Sturmbannführer Wilhelm Blühm (1942 – July 1943) SS-Sturmbannführer Hans Eckhardt (July–December