At the end of the Second World War, the repression of collaboration in Belgium fell under the jurisdiction of military justice which faced an unprecedented influx of complaints against so-called ‘traitors’. This article examines the procedures and trials concerning a particular group of Belgian citizens: the gendarmes. This study seeks, first, to quantify and characterize this repressive phenomenon. It then examines the accusations brought against the gendarmes and the development of a penal policy toward these State agents. The aim is to determine whether, in the eyes of justice, the gendarmes were regarded as ‘ordinary’ collaborators or whether their military identity prevailed. In doing so, we seek to understand how military justice, through its actions, contributed to transforming the gendarmerie profession in postwar Belgium.