Unlawful Combatants brings the study of irregular warfare back into the centre of war studies. The experience of recent and current wars in Afghanistan, Iraq, Libya, and Syria showed that the status and the treatment of irregular fighters is one of the most central and intricate practical problems of contemporary warfare. Yet, the current literature in strategic studies and international relations more broadly does not problematize the dichotomy between the regular and the irregular. Rather, it tends to take it for granted and even reproduces it by depicting irregular warfare as a deviation from the norm of conventional, inter-state warfare. In this context, irregular warfare is often referred to as the new wars and is associated with the erosion of statehood and sovereignty more generally. This obscures the fact that irregulars such as rebels, guerrillas, insurgents and terrorist groups have a far more ambiguous relationship to the state than the dichotomy between the state and non-state actors implies. They often originate from states, are supported by states and/or aspire to statehood themselves.