[Footnote 183: As, for instance, Spain in 1898, at the outbreak of the war with the United States of America, see Moore, V. pp. 375-380.] [Footnote 184: Thus American and English Courts--see the cases of the _Society for the Propagation of the Gospel_ v. _Town of Newhaven_ (1823), 8 Wheaton 464, and _Sutton_ v. _Sutton_ (1830), 1 Russel & Mylne, 663--have declared that article IX. of the treaty of Nov. 19, 1794, between Great Britain and the United States was not annulled by the outbreak of war in 1812. See Moore, V. § 779 and Westlake, II. p. 30; see also the foreign cases discussed by Jaconnet, _op. cit._ pp. 168-179.] [Footnote 185: See above, vol. I. §§ 18, 492, 555-568_b_.] [Footnote 186: The Institute of International Law is studying the whole question of the effect of war on treaties; see Politis, _l.c._, and especially _Annuaire_, XXIV. (1911), pp. 201-213, and 220-221.] [Sidenote: Precarious position of Belligerents' subjects on Enemy Territory.] § 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