Schaper's death squad was deployed in the newly formed "Bezirk Bialystok" district soon after the German invasion of the Soviet Union. Himmler visited Białystok on 30 June 1941 and pronounced that more forces were needed in the area, because the massive chase after the fleeing Red Army left behind a security vacuum. On 3 July an additional formation of "Schutzpolizei" arrived in the city from the General Government, led by SS-"Hauptsturmführer" Wolfgang Birkner, veteran of "Einsatzgruppe" IV from the Polish Campaign. The relief unit, called "Kommando Bialystok", was sent in by SS-"Obersturmbannführer" Eberhard Schöngarth on orders from the Reich Security Main Office (RSHA), due to reports of Soviet guerrilla activity in the area with Jews being of course immediately suspected of helping them. On 10 July 1941 Schaper's "Einsatzgruppe" was subdivided into dozens of smaller commandos ("Einsatzkommandos") numbering from several to several scores of people whose mission was to kill Jews, alleged communists and Soviet NKVD collaborators in captured territories often far behind the advancing German front. The entire "Einsatzgruppe" employed the same, systematic method of mass killing in many Polish villages and towns in the vicinity of Białystok. Schaper's murderous rampage south-east of East Prussia included Wizna (end of June), Wąsosz (5 July), Radziłów (7 July), Jedwabne (10 July), Łomża (early August), Tykocin (22–25 August), Rutki (4 September), Piątnica, Zambrów as well as other locations.