While in modern states military justice was primarily intended to deal with deviant soldiers, the experience of long-term military occupations led military courts to prosecute many civilians for offences against the laws of the occupying power. The Belgian case is exceptional in this regard. The country experienced two military occupations by Germany that in total lasted for more than 50 months (1914-1918, 1940-1945), and many civilians were prosecuted by military courts both during and after these occupations. Recent research has highlighted the new functions of attributed to military justice and the ambiguous treatment of civilians by the military during the two world wars. This article seeks to explore the twin phenomena of the civilian militarization and the civilization of military justice between 1914 and 1950, and the consequences of these tensions for the place of military justice in democratic society in the 21st century. the two Belgian experiences of war, occupation, and postwar normalisation highlight the ambiguity of the prosecution of civilians by military tribunals as an extraordinary and effective substitute for restoring order and political retribution. Military justice could be used as an instrument of de-civilisation, focusing repression on groups that collaborated with the occupying forces. But it can also be seen as an instrument of re-civilisation.