Historically military occupation is of relatively recent origin. The brute facts which create it are clearly not. The use of force, or threat thereof, to establish the presence of the armed forces of one state or community in the territory of another is coterminous with recorded history, but this is not what constitutes or defines military occupation. The stark contrast between the assumption of the immediate displacement of sovereignty by virtue of the possession of territory, the policy of conquest, and that of military occupation, as drawn by nineteenth century commentators, may be overdrawn. Nevertheless, despite the uncertainties about title of territory, sovereignty and mere conquest before the French Revolution, faintly reflected in passing comments by international lawyers, it is true that a distinct concept of military occupation, as articulated in memoirs, commentaries, court judgments, military codes and international treaties, only emerged in the nineteenth century.

This conceptual refinement culminated in the Hague Regulations of 1907, especially in the brief Article 43 that has exerted great influence upon subsequent debate about military occupation. The definition of military occupation as occurring under the condition of the ‘authority of the legitimate power having in fact passed into the hands of the occupant’ is both a perceptive summary of the incipient understanding of military occupation before the Hague Regulations and remains a normative limit upon the claims of the occupier.