§ 57. It must be emphasised that war nowadays is a contention of States _through their armed forces_. Those private subjects of the belligerents who do not directly or indirectly belong to the armed forces do not take part in the armed contention: they do not attack and defend, and no attack is therefore made upon them. This fact is the result of an evolution of practices totally different from those in vogue in former times. During antiquity and the greater part of the Middle Ages war was a contention between the whole of the populations of the belligerent States. In time of war every subject of one belligerent, whether an armed and fighting individual or not, whether man or woman, adult or infant, could be killed or enslaved by the other belligerent at will. But gradually a milder and more discriminative practice grew up, and nowadays the life and liberty of such private subjects of belligerents as do not directly or indirectly belong to their armed forces are safe, as is also, with certain exceptions, their private property. This is a generally admitted fact. But opinions disagree as to the general position of such private subjects in time of war. The majority of the European continental writers for the last three generations have propagated the doctrine that no relation of enmity exists between belligerents and such private subjects, or between the private subjects of the respective belligerents. This doctrine goes back to Rousseau, _Contrat Social_, I. c. 4. In 1801, on the occasion of the opening of the French Prize Court, the famous lawyer and statesman Portalis adopted Rousseau's[63] doctrine by declaring that war is a relation between States and not between individuals, and that consequently the subjects of the belligerents are only enemies as soldiers, not as citizens. And although this new doctrine did not, as Hall (§ 18) shows, spread at once, it has since the second half of the nineteenth century been proclaimed on the European continent by the majority of writers. British and American-English writers, however, have never adopted this doctrine, but have always maintained that the relation of enmity between the belligerents extends also to their private citizens. [Footnote 63: See Lassudrie-Duchêne, _Jean Jacques Rousseau et le droit des gens_ (1906).]