Initially, the Police Battalion 101 (German: Polizeibataillon 101) guarded Polish prisoners of war behind German lines, and carried out expulsion of Poles, called "resettlement actions", in the new Warthegau territory around Poznań and Łódź.[2] Following the personnel change and retraining from May 1941 until June 1942,[3] it became a major perpetrator of the Holocaust in occupied Poland.[1][4]