Sonderdienst were founded on 6 May 1940 by Gauleiter Hans Frank who stationed in occupied Kraków.[1] Initially, they were made up of ethnic German Volksdeutsche who lived in Poland before the attack and joined the invading force thereafter. However, after the 1941 Operation Barbarossa they also included Soviet prisoners of war who volunteered for special training, such as the Trawniki men (German: Trawnikimänner) deployed at all major killing sites of the "Final Solution".