§ 155. Assault is the rush of an armed force upon enemy forces in the battlefield, or upon intrenchments, fortifications, habitations, villages, or towns, such rushing force committing every violence against opposing persons and destroying all impediments. Siege is the surrounding and investing of an enemy locality by an armed force, cutting off those inside from all communication for the purpose of starving them into surrender or for the purpose of attacking the invested locality and taking it by assault. Bombardment is the throwing by artillery of shot and shell upon persons and things. Siege can be accompanied by bombardment and assault, but this is not necessary, since a siege can be carried out by mere investment and starvation caused thereby. Assault, siege, and bombardment are severally and jointly perfectly legitimate means of warfare.[295] Neither bombardment nor assault, if they take place on the battlefield, needs special discussion, as they are allowed under the same circumstances and conditions as force in general is allowed. The only question here is under what circumstances assault and bombardment are allowed outside the battlefield. The answer is indirectly given by article 25 of the Hague Regulations, where it is categorically enacted that "the attack or bombardment, by any means[296] whatever, of towns, villages, habitations, or buildings, which are not defended, is prohibited." Siege is not specially mentioned, because no belligerent would dream of besieging an undefended locality, and because siege of an undefended town would involve unjustifiable violence against enemy persons and would, therefore, be unlawful. Be this as it may, the fact that defended localities only may now be bombarded, involves a decided advance in the view taken by International Law. For it was formerly asserted by many writers[297] and military experts that, for certain reasons and purposes, undefended localities also might in exceptional cases be bombarded. But it must be specially observed that it matters not whether the defended locality be fortified or not, since an unfortified place can be defended.[298] And it must be mentioned that nothing prevents a belligerent who has taken possession of an undefended fortified place from destroying the fortifications by bombardment as well as by other means.
[295] The assertion of some writers—see, for instance, Pillet, pp. 104-107, and Mérignhac, p. 173—that bombardment is lawful only after an unsuccessful attempt of the besiegers to starve the besieged into surrender is not based upon a recognised rule of the Law of Nations.
[296] The words by any means whatever were inserted by the Second Peace Conference in order to make it quite clear that the article is likewise to refer to bombardment from air-vessels.
[297] See, for instance, Lueder in Holtzendorff, IV. p. 451.
[298] See Holls, The Peace Conference at the Hague (1900), p. 152.
Assault, how carried out.
§ 156. No special rules of International Law exist with regard to the mode of carrying out an assault. Therefore, only the general rules respecting offence and defence find application. It is in especial not[299] necessary to give notice of an impending assault to the authorities of the respective locality, or to request them to surrender before an assault is made. That an assault may or may not be preceded or accompanied by a bombardment, need hardly be mentioned, nor that by article 28 of the Hague Regulations pillage of towns taken by assault is now expressly prohibited.
[299] This becomes indirectly apparent from article 26 of the Hague Regulations.
Siege, how carried out.
§ 157. With regard to the mode of carrying out siege without bombardment no special rules of International Law exist, and here too only the general rules respecting offence and defence find application. Therefore, an armed force besieging a town may, for instance, cut off the river which supplies drinking water to the besieged, but must not poison[300] such river. And it must be specially observed that no rule of law exists which obliges a besieging force to allow all non-combatants, or only women, children, the aged, the sick and wounded, or subjects of neutral Powers, to leave the besieged locality unmolested. Although such permission[301] is sometimes granted, it is in most cases refused, because the fact that non-combatants are besieged together with the combatants, and that they have to endure the same hardships, may, and very often does, exercise pressure upon the authorities to surrender. Further, should the commander of a besieged place expel the non-combatants in order to lessen the number of those who consume his store of provisions, the besieging force need not allow them to pass through its lines, but may drive them back.[302]