The First World War unleashed a paroxysm of violence, both within Europe and overseas. Marking a major radicalisation of warfare, the extent of this violence and its effect on societies has long attracted the attention of scholars. In the interwar period, accounting for how violence was collectively represented and sanctioned through cultural practices was an underlying theme of the work of Marc Bloch, Sigmund Freud and Jean Norton Cru, among others. Later military historians analysed the brutal nature of trench combat on the western front in enormous detail. More recently, there has been a new wave of historical analysis, exploring the cultural context of combatant violence, both on the battlefield and against civilian populations; this has been accompanied by an ongoing debate as to how the war contributed to a violent European post-war political climate. Yet despite this wealth of scholarship, one crucial aspect of wartime violence has been largely overlooked. Violence against the estimated 7 to 9 million prisoners of war taken in the conflict has not been addressed in the existing historiography, with the exception of the battlefield practice of prisoner killing; however, even this subject has largely only been briefly discussed as part of broader debates on the nature of trench warfare. The scale of violence against captives remains unknown.