HOSTILITY. – In the law of nations, this term designates the use of coercive measures against another State in order to bend its will and force it to accept the desired solution of a dispute that could not or would not be resolved through ordinary means. The hostile act does not, in and of itself, always interrupt peaceful relations between the contending parties unless it is the manifestation of the intention to provoke a state of war through it; hence modern international law distinguishes hostility in peacetime from hostility in wartime or acts of war, with respect to which the contending parties comport themselves differently.
I. HOSTILITY IN PEACETIME
With regard to the former, the most common doctrine, inspired by the canons of the positivist school, does not contest its lawfulness; indeed, it approves its use, basing itself on the general principle according to which the State would always and in every case be permitted to adopt those measures it deems appropriate to defend its rights or assert its interests, provided that no positive norm of the international legal order forbids II. Outside the provisions of such an order, the State would retain its original freedom, and since the hostile act falls within this sphere—being forbidden by no specific norm—it should be regarded as a lawful juridical act, irrespective of the motives that provoke II. To reinforce this theoretical argument, it is customary to adduce the existence of a customary norm, inferred from the behavior of States, which have always resorted to coercive methods with full sovereign discretion. The theory thus formulated denies the existence of certain fundamental norms of justice, inherent in international society itself, which impose themselves by their intrinsic force upon the will of States and regulate all their actions, including the use of coercive means; it elevates to the criterion of their relations the force not subjected to law, resting upon a false conception of their original freedom, which can never be absolute but is objectively and intrinsically limited. Within this framework, legal voluntarism plays its part, reducing all law to the positive expression of the will of States, and the more general concept of sovereignty, understood as power limited only by law, by the very will posited or accepted.
Catholic doctrine cannot accept these theoretical positions. Instead, proceeding from the principle that force, being in itself neither good nor bad intrinsically, cannot receive the seal of moral and juridical legitimacy unless it is directed toward the attainment of an end that is just in its essence, it reaffirms its stance regarding hostility in peacetime, declaring it lawful when placed in the service of right for its defense or reparation, and unlawful otherwise. It does not exclude the faculty of the State to resort to violent means, but only under the higher norms of natural justice and within their limits, thereby rejecting the dual axiom of voluntarism and unlimited sovereignty. Acts of hostility that do not, by their mere commission, interrupt ordinary relations are considered: retaliation, sequestration, embargo, reprisals, and pacific blockade.
Retaliation consists in countering an act contrary to law, interests, and equity with an act of the same kind, in order to compel a State to recognize its wrong and desist from the measures it has taken. By sequestration, a State takes possession of property belonging to another in order to exact reparation for an injury suffered. Embargo is a special form of sequestration directed against the merchant vessels of the opposing State, thereby excluding warships. Regarding reprisals, see the corresponding entry. Blockade, finally, occurs when the ports or places of the adversary are closed to all commerce, and may thus be maritime or continental. It is superfluous to note how, in the use of these means permitted by modern international law, the State must proceed with caution, keeping in mind not only the most universal norms of justice—from which alone the lawfulness of its procedure can derive—but also the well-being of the international community and the possible complications harmful to it, to which, according to the principle already established by Vitoria with regard to war, even the defense of a certain right remains subordinate. In the case of retaliation and reprisals, moreover, every act contrary to the laws of humanity and the most fundamental rights of the human person must be considered unlawful, even if committed by another State.
II. HOSTILITY IN TIME OF WAR OR ACTS OF WAR
1. Commencement of hostilities
For a long time, it was customary not to initiate hostilities without first making known to the adversary, in some manner, the intention to submit the pending dispute to the judgment of arms. To this end, heralds were usually dispatched, who, by means of letters of defiance or verbally, made known the will of their sovereigns and the reasons for which they deemed recourse to violent means necessary. Subsequently, this practice fell into disuse; States, driven both by new conceptions of warfare and by allegedly exigent military requirements—which suggested a swift commencement of hostilities in order to catch the enemy by surprise—began to dispense with all formalities, launching attacks without any prior declaration. This new practice, which replaced the older one, must be regarded as a progressive departure from the natural norms of just war. War, in fact, is legitimate only against a State guilty of a grave violation of the rights of others, which has stubbornly refused to provide peaceful reparation. It thus assumes the character of a last resort or extreme means, morally and juridically admissible only when ordinary means of resolution have been exhausted in vain. It is therefore necessary that, before resorting to force against one who has violated the law, time be granted for the possibility of repairing, if desired, the injury committed. The original incident must be the subject of prior negotiation, conciliatory proposals, and compromise, and, if possible, submitted to arbitration in order to achieve a consensual agreement. If all efforts to resolve the conflict peacefully fail, a solemn warning must always precede the commencement of hostilities, bringing the obdurate State face to face with its responsibilities and making it aware that the hour of negotiation has passed. To avoid destroying the last possibility of a peaceful solution that may still exist at the moment of the declaration of war, a reasonable interval should be fixed between the declaration and the actual commencement of hostilities.This principle, derived from a moral conception of war, was adopted by the Hague Conference of 1907, which in Article 1 of Convention III stipulated that hostilities (o.) were not to be commenced by the contracting powers without a prior and unequivocal notice, either in the form of a reasoned declaration of war or an ultimatum with a conditional declaration of war. The same convention, however, neither requires nor specifies that an interval must elapse between the notification and the commencement of hostilities, since attempts by some delegations to establish a minimum term of 24 hours failed. The exceptions to the aforesaid rule are numerous, particularly after its acceptance, so numerous as to suggest that States do not feel bound by it as they ought, opposing to it a contrary custom which is condemnable on higher grounds of morality and justice. The initiation of hostile acts, accompanied by a clear intent to establish a state of war, even if not preceded by any summons or declaration, puts an end to peaceful relations in every supposition, suspends the ordinary law governing them, and gives rise to the particular relationship of belligerency, bringing into force a new category of norms by which the conduct of hostilities is governed throughout the war.
2. Conduct of hostilities
At the present time, there are not a few political theories, or seemingly juridical ones, which maintain the full liberty of States in the use of offensive means against the adversary, to break their resistance rapidly. It has been asserted that war, essentially inhuman, cannot be humanized, and even that the most humane war would be one which, by ruthless methods, shortens the duration of the struggle by breaking the enemy’s strength more swiftly. It has further been argued, from a juridical standpoint, that since war is a complex of hostile acts outside the law and contrary to the existing law among States, it cannot in itself be subject to law, and therefore falls within that sphere of unregulated freedom where everything is permitted. A relationship of force, which awaits regulation by force, can have no criterion other than force itself, which must be left free to exert its pressure upon the adversary by all means at its disposal.The theses just outlined, which are linked to conceptual positions (v. GUERRA), share a common foundation in the amoralism of armed struggle and the cult of force as the generator of law, and cannot be accepted by Catholic doctrine, which rejects them emphatically. War is not the unleashing of cosmic forces or biological instincts of the species, as some have sought to define it, but a struggle between men and therefore involves a series of human acts, which, like all other human acts, are subject to the laws of morality, justice, and humanity. Moreover, war is in itself an exercise of force, whose justification is derived from an end—the defence and restoration of threatened or violated right—and hence the limits within which hostilities must be contained are derived from that same end. This finalistic principle, implicitly enunciated by Vitoria when he affirms that in a just war one has the right to do whatever is necessary for the defence of the public good, has been consistently applied to the conduct of hostilities by subsequent Catholic tradition, by Suárez, Molina, and other later authors.
To this has been joined the distinction, with regard to the faculty of offence, between *innocentes* and *innocentes*, that is, between combatants and non-combatants, with the moral and juridical rule of sparing the latter from direct attack. Thus a principle of humanity was made to prevail over the use of force, first practically imposed by ecclesiastical authorities in the Peace of God, and later theorized as a source of moral obligation. The foundations upon which Catholic thought built its doctrine on the conduct of hostilities are therefore: the distinction between lawful and unlawful means of offence, deduced from the finalistic criterion of war; and that between combatants and non-combatants, derived from the same principle and from the laws of humanity; to these, in a subordinate manner, was added that of loyalty, already hinted at by St. Thomas (Sum. Theol., 2a-2ae, q. 40, a. 3), who excluded the lawfulness in time of war of deceiving the enemy, of uttering falsehoods, or of failing to keep promises, since “quedam iura bellorum, et foedera etiam inter ipsos hostes servanda.”
The practical consequences of these principles regarding what is lawful or unlawful in the conduct of hostilities are clear and evident. Systematically, they were best deduced by Taparelli. The purpose of war, he says, is to restore order by force; consequently, everything that cannot offer resistance must not be destroyed. Hence, every form of vandalism is condemned—the wanton destruction of houses and property, the indiscriminate slaughter of old men, women, and children. Every unnecessary evil, not required to break the enemy’s strength, is forbidden in humane warfare by the very end of war itself. The same law of avoiding unnecessary evil forbids among nations the use of certain means of offence whose effects cannot be controlled and whose harm is directed against the forces of resistance. To spread contagion, to poison waters, and other similar chemical or bacteriological means must be regarded as forbidden. Taparelli adds further: if it is forbidden to do an unnecessary evil, then a fortiori it is forbidden to do moral evil. Treachery, perjury, parricide, or sacrilege must not occur in war between men, and the sanctity of truces and armistices must be observed, as must respect for the dead, humane treatment of the wounded, discretion in the requisitioning of food, and so forth. The uncertainties regarding some bellicose procedures, still deemed lawful by medieval and 16th-century authors under the pressure of customs then in vogue, were resolved in the more mature elaboration of Taparelli, which has now become common doctrine in Catholic thought.
3. Positive law and hostilities
Positive international law has adopted the principles expounded and their practical consequences. In various conventions, States have gradually expanded the code of laws of war, so as to mitigate appreciably, at least on the level of agreements, the harshness of hostilities. In this connection, the following should be recalled in chronological order: the Geneva Convention of 1864 for the amelioration of the condition of the wounded in armies; the Declaration of St. Petersburg of 1868 for the exclusion of the use of explosive bullets; the various Hague Conventions of 1899, 1904, and 1907 on the laws and customs of land and sea warfare; the Geneva Convention of 1906 for the assistance of the sick and wounded; the Washington Treaty of 1922 for the protection of the lives of neutrals and non-combatants and for the prohibition of the use of asphyxiating gases and chemical means; the Geneva Protocol of 1925 concerning the prohibition of asphyxiating, poisonous gases, and bacteriological means; and finally the Geneva Convention of 1929 for the amelioration of the condition of the wounded and sick and of prisoners of war.The outline just sketched of the numerous international conventions shows how positive law has advanced, particularly during the last century, adapting itself to the higher demands of natural justice and the laws of humanity. Without descending to particular determinations, to realize this progress it will suffice to note the general lines. It must be considered as a norm accepted by the majority of States the principle enunciated in Article 23 of the Hague Regulations of 1907, according to which belligerents do not have unlimited rights in the choice of means of offence. Their right is circumscribed both by the aims for which war is waged—means that are unnecessarily cruel being excluded—and by the laws of humanity. This criterion, which was explicitly mentioned in the preamble to the St Petersburg Declaration of 1868, informs all the positive provisions on the conduct of war. Furthermore, the distinction between combatants and non-combatants, with the consequent prohibition against directly harming the latter, must also be regarded as a norm of contemporary international law of war.
It should also be noted that not a few articles of the Hague Convention of 1907 lay down the obligation of good faith, prohibiting all those procedures that may deceive the enemy and cannot be reduced to military stratagem.
With regard to means of offence, the Regulations annexed to the Convention just recalled forbid the use of poison and poisoned weapons. This provision must be supplemented by the Second Hague Declaration of 1899, which prohibits projectiles that expel asphyxiating or deleterious gases, a prohibition reiterated by the Washington Convention of 1922. It is followed by the prohibition against killing or causing to be killed treacherously individuals belonging to the enemy State, killing or wounding an enemy no longer capable of defence or who has surrendered, and using weapons and projectiles likely to cause unnecessary suffering. Special provisions regulate the treatment of the wounded, sick, and prisoners of war, to whom death may not be inflicted.
The use of stratagems is not prohibited; however, the Hague Regulations of 1907 expressly forbid the illegitimate use of the white flag, enemy flags and uniforms, and the distinctive signs of the Red Cross, as well as all those procedures that constitute acts of perfidy or are contrary to military honour. The giving of no quarter, admitted by some particular legislations in cases of necessity, is also forbidden as a convenient means of evading the strict prescriptions of the law. Necessity can never justify the violation of the norms of justice and humanity.
4. The Church and the conduct of war — The provisions of positive international law briefly described above derive from the Christian tradition, applied through the ecclesiastical hierarchy, in softening the customs of war.
The movement in favour of a greater sense of humanity in the conduct of war began in the Middle Ages in France, where several local and regional councils issued prescriptions to this effect. The Council of Narbonne of 990, for example, imposed excommunication on those who had struck the monks of Cluny and took other measures to restrain war (Hefele-Leclercq, IV, pp. 869-70 and 869 note 2). In 989, provisions in favour of combatants had already been extended by the Council of Charroux near Poitiers from ecclesiastics and Church property to peasants and the poor, imposing excommunication on those who deprived them of their goods, as well as on travellers and merchants (loc. cit.). Under Church auspices, around 997, a league for the maintenance of peace was created, in which laymen participated with deliberative functions, with the obligation to assist the bishop in repressing acts of violence committed within his territory (loc. cit.), later transformed in 1098 into a compulsory peace association, in which all men from the age of fifteen were required to enlist and take an oath. The Holy See did not fail to promote the Peace of God; as early as 1030, the legates of Pope John XIX went from council to council to impose it and to anathematize those who contravened it (ibid., p. 960 ff.).
To soften the customs of war, the Truce of God also contributed. The Council of Elne of 1027 (ibid., p. 969 ff.), after confirming the protective provisions for clerics, monks, and women, determined that from the hour of Saturday evening until the first hours of Monday it was forbidden for all to attack their enemy. The Truce of God, at first a simple application of the precept of festive rest, was extended to other days and to particular liturgical times, such as Advent and Lent. A legate of Pope Alexander II introduced it into Spain in 1068; two councils, that of Melfi in 1089 and of Troia in 1099, did so in Italy (ibid., V, pp. 345 ff., 371 ff.). In 1093, Urban II, present at the Council of Clermont, wished to extend the institutions of peace to the whole Church in view of the Crusade. The Peace of God and the Truce of God would be confirmed by Paschal II (1107) and by Callistus II (1110, ibid., V, p. 581 ff.).
With regard to the use of means of offence, Innocent II at the Lateran Council of 1139 forbade the use of ballistae and arrows. In 1179, Alexander III renewed the prescription that priests, clerics, monks, conversi, pilgrims, merchants, peasants travelling or engaged in agriculture, and their animals, should enjoy appropriate security. These prohibitions and prescriptions were renewed by Innocent III (ibid., V, pp. 728-29, 1103). The Church also exercised a beneficial influence on the customs of war through the institution of chivalry and the Third Orders.
It is a common opinion among historians of international law today that the laws on the conduct of war derive particularly from the constant efforts of the Church, which succeeded in instilling into the still savage souls of the peoples certain principles of humanity, which, later developed theoretically by the first Catholic systematizers of international law, have become the heritage of civilized nations as part of modern positive law.