§ 100. The outbreak of war affects likewise such subjects of the belligerents as are at the time within the enemy's territory. In former times they could at once be detained as prisoners of war, and many States, therefore, concluded in time of peace special treaties for the time of war expressly stipulating a specified period during which their subjects should be allowed to leave each other's territory unmolested.[187] Through the influence of such treaties, which became pretty general during the eighteenth century, it became an international practice that, as a rule, enemy subjects must be allowed to withdraw within a reasonable period, and no instance of the former rule has occurred during the nineteenth[188] century. Although some[189] writers even nowadays maintain that according to strict law the old rule is still in force, it may safely[190] be maintained that there is now a customary rule of International Law, according to which all such subjects of the enemy as have not according to the Municipal Law of their country to join the armed forces of the enemy must be allowed a reasonable period for withdrawal. On the other hand, such enemy subjects as are active or reserve officers, or reservists, and the like, may be prevented from leaving the country and detained as prisoners of war, for the principle of self-preservation must justify belligerents in refusing to furnish each other with resources which increase their means of offence and defence.[191] However that may be, a belligerent need not allow[192] enemy subjects to remain on his territory, although this is frequently done. Thus, during the Crimean War Russian subjects in Great Britain and France were allowed to remain there, as were likewise Russians in Japan and Japanese in Russia during the Russo-Japanese War, and Turks in Italy during the Turco-Italian War. On the other hand, France expelled all Germans during the Franco-German war in 1870; the former South African Republics expelled most British subjects when war broke out in 1899; Russia, although during the Russo-Japanese War she allowed Japanese subjects to remain in other parts of her territory, expelled them from her provinces in the Far East; and in May 1912, eight months after the outbreak of the Turko-Italian War, Turkey decreed the expulsion of all Italians, certain classes excepted. In case a belligerent allows the residence of enemy subjects on his territory, he can, of course, give the permission under certain conditions only, such as an oath to abstain from all hostile acts or a promise not to leave a certain region, and the like. And it must be especially observed that an enemy subject who is allowed to stay in the country after the outbreak of war must not, in case the forces of his home State militarily occupy the part of the country inhabited by him, join these forces or assist them in any way. If, nevertheless, he does so, he is liable to be punished for treason[193] by the local Sovereign after the withdrawal of the enemy forces.
[187] See a list of such treaties in Hall, § 126, p. 107, note 1.
[188] With regard to the 10,000 Englishmen who were arrested in France by Napoleon at the outbreak of war with England in 1803 and kept as prisoners of war for many years, it must be borne in mind that Napoleon did not claim a right to make such civilians prisoners of war as were at the outbreak of war on French soil. He justified his act as one of reprisals, considering it a violation of the Law of Nations on the part of England to begin hostilities by capturing two French merchantmen in the Bay of Audierne without a formal declaration of war. See Alison, History of Europe, V. p. 277, and Bonfils, No. 1052.
[189] See Twiss, II. § 50; Rivier, II. p. 320; Liszt, § 39, V.; Holland, Letters upon War and Neutrality (1909), p. 39.
[190] See Land Warfare, § 12.
[191] See Land Warfare, § 13.
[192] See above, [vol. I. § 324].
[193] See above, [vol. I. § 317], p. 394, where the case of De Jager v. Attorney General is discussed.
Persona standi in judicio on Enemy Territory.