During the Second World, numerous (small) occupier and collaborator military units operated in Slovenian territory that are better known for their war crimes against civilians rather their involvement in counterguerrilla warfare. One of these units was also the mounted police detachment Serbia (Polizei-Reiter-Abteilung Serbien), which arrived in Prlekija no earlier than the autumn of 1944 as part of the general retreat of German and collaborator units from Serbia. Based on wartime and postwar archival documents as well as postwar literature, the article at hand presents and analyses the activities performed by this paramilitary unit, which was primarily composed of foreigners but under German command. Whereas in Prlekija, the unit engaged in fights against local Partisans, its members entered the local history by inflicting the worst kind of terror on the local population.