[Footnote 234: Says Vattel, III. § 159: "Mais ce n'est point une loi de la guerre d'épargner en toute rencontre la personne du roi ennemi; et on n'y est obligé que quand on a la facilité de le faire prisonnier." The example of Charles XII. of Sweden (quoted by Vattel), who was intentionally fired at by the defenders of the fortress of Thorn, besieged by him, and who said that the defenders were within their right, ought to settle the point.] [Footnote 235: See Baty, _International Law in South Africa_ (1900), pp. 84-85.] [Sidenote: Refusal of Quarter.] § 109. However, the rule that quarter must be given has its exceptions. Although it has of late been a customary rule of International Law, and although the Hague Regulations now expressly stipulate by article 23 (_d_) that belligerents are prohibited from declaring that no quarter will be given, quarter may nevertheless be refused[236] by way of reprisal for violations of the rules of warfare committed by the other side; and, further, in case of imperative necessity, when the granting of quarter would so encumber a force with prisoners that its own security would thereby be vitally imperilled.[237] But it must be emphasised that the mere fact that numerous prisoners cannot safely be guarded and fed by the captors[238] does not furnish an exceptional case to the rule, provided that no vital danger to the captors is therein involved. And it must likewise be emphasised that the former rule is now obsolete according to which quarter could be refused to the garrison of a fortress carried by assault, to the defenders of an unfortified place against an attack of artillery, and to the weak garrison who obstinately and uselessly persevered in defending a fortified place against overwhelming enemy forces. [Footnote 236: See Pradier-Fodéré, VII. Nos. 2800-2801, who opposes this principle but discusses the subject in a very detailed way.] [Footnote 237: See Payrat, _Le Prisonnier de Guerre_ (1910), pp. 191-220, and _Land Warfare_, § 80.] [Footnote 238: Accordingly, the Boers frequently during the South African War set free British soldiers whom they had captured.] [Sidenote: Lawful and Unlawful Means of killing and wounding Combatants.]