VII. On War

What is war? War is a fight of a multitude against an external multitude, undertaken by the legitimate authority of Princes, for defending the good of the commonwealth or for vindicating an injury inflicted upon it. War differs from a brawl because a brawl is a fight between private persons, of a few or of individuals against a few or individuals. It differs from sedition, because sedition is the attack of a multitude against a multitude in the same commonwealth or society. A brawl proceeds from an inordinate will. And therefore a brawl always imports sin. And in him indeed who unjustly attacks another, it is per se mortal sin; for to inflict harm on a neighbor, even by natural work, is not without mortal sin. But because sedition has a special good to which it is opposed, namely the unity and peace of the multitude, it is a special sin. It is opposed to justice and to the common good, insofar as it inflicts harm on the commonwealth and its citizens. "And therefore from its genus it is mortal sin, and so much the more grave as the common good which is attacked through sedition is greater than private good.... But those who defend the common good by resisting them are not to be called seditious, just as neither are those who defend themselves called brawlers." S. Th. 2. 2, q. 42, a. 2. S. Th. 2. 2, q. 40, a. 1; q. 41, a. 1; q. 42, a. 1.

How many kinds of war are there? One war is defensive, another offensive. Offensive war pertains to vindicative justice, and cannot be instituted except by the authority of the supreme Prince. But defensive war looks only to this, that force brought by another commonwealth be repelled by force. "Moreover, since all laws permit force unjustly brought to be repelled by force, hence defensive war can be undertaken not only by public authority, but also by private authority of those invaded by the enemy, as is found in L. 3 ff. de Iust. et iur. Meanwhile, however, between war undertaken by private and public authority there is this distinction: that those fighting in defensive war by private authority are bound to the moderation of blameless defense, stopping in only necessary and sufficient defense; on the contrary, those fighting in defensive war undertaken by public authority can justly proceed further offensively to vengeance for the injury inflicted." Struggl 40; L. 402; S. Th. 2. 2, q. 40, a. 1.

Is war lawful? - The lawfulness of defensive war is clear from this, that if it is lawful for a private man to repel force by force, the same certainly will be lawful for the whole society.

But the lawfulness of offensive war, if the due conditions concur, is clear both from the common authority of Catholics and because by natural law it is lawful not only to ward off an injury while it is being inflicted unjustly on someone, but also to vindicate and remove it by public authority after it has been inflicted, lest it be inflicted again thereafter. Therefore supreme Princes, who on earth do not have a higher judge, can vindicate injuries inflicted on them by another Prince; and this cannot be done except through offensive war. Therefore. C. Iustum 1, c. 23, q. 2; C. Dominus 2 ib.; Struggl 41; Ithur. Cas. 40, n. 13; L. 402; S. Th. 2. 2, q. 40, a. 1; E. M. Consequently war is lawful for bringing help to another people which is waging a lawful war. E. M. 757.

What are the conditions for beginning, continuing, and ending war lawfully and justly? - R. To the 1st: 1. Public authority, that is, supreme authority, recognizing no other superior in civil matters. The reason is that where a greater authority is had, this must judge concerning the dispute. 2. A just and grave cause, which is preponderant over the inconveniences going to follow from war, for example, a kingdom or province to be recovered, or a grave injury to the commonwealth to be warded off, or a rebellion of subjects to be repressed, etc. For since from war so many evils come to the body and soul of many, it is not to be attempted except in extremes. 3. Morally certain right. The reason is: 1. because a possessor in good faith cannot be despoiled of the thing possessed, unless it is established that he unjustly retains it. 2. Because for positing the cause of most grave evils, both of private persons and of society itself, such as killings, injustices, corruptions of morals, and other such things, which ordinarily follow war, moral certainty of one's right seems to be required. Thus far more probably and more truly, St. Liguori 404, Pal., Tamb., and others against many, of whom some think that only greater probability suffices, others that equal probability suffices. But theologians commonly teach that lesser probability by no means suffices. 4. That before war, condign satisfaction be demanded from the adverse party; if it is offered, it must be accepted from justice, for where war ceases to be necessary, it also ceases to be just. 5. Right intention is required, namely that good be promoted and evil avoided, not by cupidity or cruelty, but by zeal for peace. L. 403, 405; S. Th. 2. 2, q. 10, a. 8; q. 40, a. 1; Verricelli tr. de Apost. Mission. t. 13, q. 128, s. 17, section 13.

R. To the 2nd: Even after mutual aggression and conflict, when some have already fallen on the side of him who wages a just war, condign satisfaction must be accepted and the war interrupted, if that is offered by the adversary Prince; if not from the rigor of justice, at least for the most part from charity, provided that the other party is willing to compensate all expenses already made, and it is not necessary for the public good that his insolence be beaten back. The 1st reason is that then war already ceases to be necessary for the end. The 2nd reason is that, since in a vindicative war, after many have already fallen, it is almost impossible to give condign satisfaction, the offended Prince, from a war actually begun, is not bound from justice, but rather from charity alone, to desist and to accept satisfaction. Laymann l. 2, tr. 3, c. 12, n. 5; L. 405.

R. To the 3rd: In offensive war, after the thing owed has been recovered and every indemnity, or after the injury has been sufficiently vindicated, the victor is bound to accept peace furnished with just conditions. The same is true of the victor in defensive war, after he has sufficiently vindicated the injury inflicted on him. The reason is that excess would be against the right of vindicative justice, indeed even of commutative justice. Besides, the end of war is peace and security. Therefore, once these have been sufficiently obtained, war, as an atrocious means, must be desisted from. Moreover also the conquered, per accidens, is often bound to accept peace, lest he expose himself and his subjects to greater danger, misfortune, or intolerable inconvenience. Struggl 44; Cajetan, Summ. v. Bellum. A nation which justly wages war can occupy the goods of enemies as much as is necessary for compensation of the damages which it has suffered, for payment of the expenses of war, and for just vengeance of the injury.

What is lawful to do against the enemy in war? - In a just war it is lawful to do all things against the enemy which are necessary and apt for obtaining the just end of war, yet according to the command and express or tacit will of the commander of the war. The reason is that he who has a right to the end also has a right to the necessary and apt means. Therefore in a just war it is lawful to do against the enemy all things which are necessary and apt for obtaining the just end of war. Which are necessary and apt; for other things harmful to the neighbor, which are not necessary for such an end, cannot justly be inflicted, and the damage afterward must be repaired. The just end of war, namely to overcome the enemies. Laym. 9; Sporer 112; Struggl 45; L. 409.

You will resolve: In a just war it is lawful to fight in open warfare, and to use ambushes and stratagems. These are not reputed lies, because the adversaries are deceived by their own fault, since those means are customarily used in war. But deceits are unlawful which cannot be guarded against by prudence. It is lawful to deprive cities of water; but it is not lawful to infect wells and fountains with poison, or otherwise to use methods of bringing slaughter which can be avoided by no human prudence, or which bring grave harm even to the innocent, or which savor of cruelty and atrocity, S. Th. 2. 2, q. 108, a. 2 ad 3; much less indeed is it lawful directly to kill the innocent, legates, cf. 737, who by the law of nations are everywhere inviolable, and likewise to suborn assassins who secretly butcher the Prince or commander of the army.

Therefore the use of any kind of weapons is lawful, provided that these are not poisoned, or lethal in another similar way. It is lawful to besiege cities and citadels, to discharge artillery against them, indeed sometimes to destroy or burn monasteries and churches, to plunder and kill in them, if, for example, enemies use a church as a citadel for defending themselves.

To use the standards of enemies in order to deceive enemies is a very true lie of fact.

Scouts also, who are sent to enemies under the appearance of friends or by another fictitious reason, and approach them asking, for example, medicines which they do not need, are not even free from a lie.

Lying, deceit, fraud are never lawful. Likewise it is sometimes lawful to give a captured city to plunder, but only for most grave reasons. This, however, is not lawful for soldiers by their own authority, but it is necessary that legitimate permission be present. And then it is in no way lawful directly to kill the innocent, under whose name come children, women, the elderly, foreigners, clerics, peasants, merchants, etc., because these have committed nothing on account of which they could be deprived of life, nor are they actual or proximate aggressors. Moreover it is not lawful per se to despoil innocent foreigners even of goods, because they are guilty neither in themselves nor in society. Likewise, when a city is given to plunder, monasteries, churches, and pious places are always excepted. C. 2 de Treg. et pac. But immovable goods by the law of war fall to the Prince or commonwealth; movable goods of use become the property of the first taker, unless custom or law is that a part fall to the Prince and community, or all be placed in common, and distribution be made to individuals with due proportion. Besides spoils, reprisals also are lawful; they are occupation by force made and retention of persons or things of enemies, which by chance or by design come into the hands of the other party, since they are certain compensations and a kind of war. They are lawful, if however: 1. It is manifestly established that citizens of the other commonwealth have done an injury. 2. If their superiors, when asked, refuse to administer justice. 3. If it is established that they culpably refuse this. 4. If the supreme Prince, the cause having been known, concedes this. 5. If no more damage is inflicted than just satisfaction requires. 6. If they are not committed against ecclesiastical persons; C. Etsi unic., de Iniur. in 6. In the conflict itself or attack it is lawful to kill all fighting against one, or existing in arms, of whatever condition, state, or sex, until they give themselves as captives, and perfect victory is obtained. But after the conflict and victory obtained, it is sometimes lawful also to kill captured or surrendered guilty persons, namely if before this they have merited death by some crime; or if this is necessary for establishing peace and security or justly vindicating the injury, unless they have surrendered with a pact of life to be preserved; or unless they are clerics, even guilty, whom after the conflict it is in no way lawful for a secular Prince to kill because of their immunity. But since soldiers today are regularly compelled and not voluntary, they also are to be held as innocent, whom it is not lawful to kill after conflict. 1 Kings 30; C. Miles 13, c. 23, q. 5; L. 409, 410; Struggl 47 seqq.; Ithur. Cas. 40, nn. 14, 17; Laym. l. 2, tr. 3, c. 12, nn. 7, 9 seqq.; S. Th. 2. 2, q. 40, a. 3; q. 66, a. 8 ad 1; q. 108, a. 1 ad 5.

Can Catholic Princes in war call heretics or even gentiles to their aid? - The first opinion universally affirms. The second opinion absolutely denies. The third opinion affirms that per se it is lawful; nevertheless per accidens by reason of scandal and harm to religion, which for the most part is present, it is unlawful. "This third opinion," says St. Alphonsus 406, "speculatively is indeed probable, but the second in practice seems altogether to be held. The reason is that it is morally impossible that, with alliance contracted with enemies of the faith, the aforesaid harms will not come to religion." Prop. 62 Syll. condemned by Pius IX; E. M.

Can soldiers wage war with doubt concerning the justice of the war? - Either the matter concerns soldiers who are subjects; or non-subjects; or hired men. If the 1st, they are bound to obey the Prince commanding, until they are altogether certain concerning the injustice of the war; for subjects are bound to obey where sin is not certain. Then, in the proposed case, they must presume the war as just, where the contrary does not clearly appear. Namely, the right of the superior possesses, so that, Augustine teaching, "perhaps the injustice of commanding makes the king guilty, but the order of serving shows the soldier innocent." L. 22 cont. Faust. c. 75.

If the 2nd, they must not fight unless they become certain of the justice of that war; for since the matter concerns the damage of a third party and indeed most grave damage, it cannot be inflicted on him before there is certainty concerning the injustice of the possessor. If the 3rd, either they were already hired before the war was declared, and the same thing must be said as of subjects; or afterward, and what was said of non-subjects holds. Luc. 3:14; L. 407, 408; Ithur. Cas. 40, n. 16; Tambur. Explic. Dec. l. 6, c. 1, par. 1, n. 9; Lugo de Iust. et Iur. d. 10, n. 144; Laym. l. c. n. 8. In an evidently unjust war, soldiers, although compelled, cannot fire upon enemies and kill or wound them. Yet if they are attacked by enemies who, if they handed over their arms, would be unwilling to grant pardon, then they can defend themselves with arms against them, as against unjust aggressors. Tambur. in Decal. l. 6, c. 1, section 1, n. 9.

Is it lawful for clerics to wage war? - Outside the cases of necessity, clerics are prohibited by canon law, under penalty of irregularity, from fighting by their own hand in war. C. Clericum D. 50; C. Eos qui c. 20. q. 3, etc. Outside the case of necessity; for in certain cases of necessity, clerics, without license of the Pope and without the penalty of irregularity, can fight by their own hand in war. Struggl 54; Laym. l. c. n. 19; S. Th. 2. 2, q. 40, a. 2.

What special obligation is present in time of war for the Prince and commanders, and for soldiers? R. To the 1st: Princes and commanders, especially in time of war, are bound to take care that soldiers observe the precepts of morals and religion, lest they be a scandal or harm to peoples. They must command nothing too dangerous to soldiers, unless because of manifest necessity; and with every zeal they must provide for their lives, and they must not rashly expose their own life to danger, lest the whole army or the whole legion lack a prudent leader. Likewise they must pay stipends to them by right administration, and with due equity distribute burdens among citizens if at any time they spend the night and stay among them; otherwise they are bound to compensate damages to them, both to soldiers and to others who have received damages from soldiers, since they are the unjust and efficaciously moving cause of these. Likewise to citizens who in time of war have suffered immense damage, a certain restitution is owed by the commonwealth. For the law of war excuses not those things which are done to citizens, but those things which harm the enemy. Nor indeed is it fair that some be burdened more than others, when the matter concerns a good common to all. By the same reason a contribution is customarily made if the merchandise of one has been thrown into the sea so that the things of others may be saved. "For the protection of the commonwealth of the faithful it is lawful to carry on just wars on feast days." S. Th. 2. 2, q. 40, a. 4; C. 1 de Treg. et pac.; Cf. here 658.

R. To the 2nd: Citizens are altogether lawfully compelled by legitimate authority, when public necessity compels, to make military service. Soldiers, however, must obey the commander in all things which regard military service, with the divine law preserved. Therefore they must keep their station, attack the enemy, and fight bravely even with danger of life. But they cannot do anything unordered, although for the utility of their own and the harm of enemies. For it is better that necessary discipline be preserved than that utility be sought at anyone's discretion with danger of harm. Soldiers who depart from the army for a time without the commander's license sin; but those who entirely desert the camp are guilty of a more grave sin. Luc. 3:14; L. 405, 407; Laym. l. c. n. 18; Cajetan, Summ. v. Bellum; Gousset 1003 seqq.

When war has been completed, are the parties bound to preserve public pacts, extorted by the force of war and of victory obtained? Gury, Cas. 410, responds affirmatively to this question. "The reason is," he says, "because public treaties were introduced by the law of nations, common to the whole human race, the common good of the human race so requiring.

For unless public pacts between so many different Princes, and between magistrates and subjects, were to be preserved in every way, no stable peace or society could consist; but a way would be opened to perpetual wars and slaughters." Reuter has the same opinion, which he affirms to be common, saying p. 3, n. 510: "Public faith given to an enemy, even one waging an unjust war, is to be preserved, provided the treaty is not objectively evil." Concerning this same question Lugo has these things: "In war, because of the public good of peace and the security of kingdoms, it is necessary that pacts be preserved on both sides, when they are made without coercion and fear; otherwise, since each one presumes that he has a just cause of war, pacts of this sort would never be preserved, which would be the greatest impediment to composing peace; just as also, because of the same reason, impunity and indemnity are owed to orators and public legates, because otherwise there could not be negotiation concerning peace, which would be a great inconvenience." De Iust. et Iur. d. 37, s. 15, n. 179. And S. Th. 2. 2, q. 40, a. 3 says: "Someone can be deceived from the deed or saying of another from the fact that something false is said to him or a promise is not kept; and that is always unlawful; and in this way no one ought to deceive enemies; for there are certain laws of wars, and treaties to be preserved even among enemies themselves." C. Noli 3, c. 23, q. 1. Laym. l. c. nn. 15, 16.