§ 1. Saint Thomas, Summa Theologiae, II–II, question 40, article 1, requires three conditions for a war to be just. The first is that there be the legitimate authority of the prince; the second, that there be a just cause which impels him to war; the third, that there be a just intention. I shall discuss these questions in order.
§ 2. Since the power of princes varies—some have no superior, while others are sent by kings to govern provinces in such a way that they nevertheless do not touch military affairs—it is rightly asked in whose power it lies to decree war.
It is certain that the right of declaring war resides in the state itself which is complete and does not receive its right from another, superior magistrate. For a complete state is one that is sufficient for itself, or αὐτάρκης, so that it can protect itself without another’s authority. For this it is necessary that it be able to carry arms against another when it cannot obtain its right in another way. For when the Romans are attacked by the Veientines, their constant and yearly enemies; when the Faliscans and Fidenates make an attack; when allies implore assistance against the Samnites; when the Tarentines insult foreigners and violate ambassadors; when it has been resolved to subdue the Picentes, allies of the enemy—there was need of someone to decree that war must be waged. For those injuries ought not to have been borne, lest the state be lost entirely.
That the right of war belongs to a complete state is taught from the fact that it can bring an action for the recovery of what has been taken and demand satisfaction. Private persons go before a judge; here there is no judge except the injured party, who is therefore superior, because those who inflicted the injury have by that very fact become answerable to the injured: by their crime they have brought it about that they must submit to judgment. For just as a private person who commits a crime in another’s territory is subjected to the judge in whose province he sinned, so too, when loss is inflicted upon a state, the state itself can judge the wrongdoers; and therefore it decrees war against others and removes impediments to the common good. But since war is an act τῆς ἐκδικητικῆς, of vindicatory justice, and thus belongs to the magistrate, it is altogether certain that the judge of him who inflicted injury is he who suffered it. Otherwise he would have no judge and no protection of justice.
§ 3. Kings ordinarily have the right of waging war, as does the senate or supreme council. Sometimes, however, by the laws of a kingdom they lack that power, and perhaps this is expedient, lest the swift indignation of kings undertake wars afterward to be regretted and to be paid for by the people. The first kings at Rome undertook war by the authority of the senate; afterward the senate used the same power, until, worn out by continual labors, the business devolved upon the people. For unwillingly did the people decree that a war must be endured at its own peril.
The Spartans, who, according to Aristotle and Xenophon, instituted their state very badly because they attended to almost one thing alone—namely war—granted their kings the right of carrying war against anyone whatsoever, and no one possessed the right to interpose or prohibit. This brought them into great calamities, since wars were aroused by the judgment of one man alone. Romulus and the kings who followed did better: they sometimes referred the matter to the Fathers and the people. Tarquin the Proud recalled everything to himself, as did Julius and Augustus; and so that they might appear to do this by right, they obtained the law of which Strabo speaks in Book XV, called the royal law. Certainly, so that war may be decreed more slowly, it is better that the consent of many be required. Yet I judge that such laws should be tempered in this way: that this right be sometimes granted to a king and sometimes denied—granted in sudden emergencies and when there is danger in delay, denied when time for deliberation can be given without danger.
§ 4. Princes who acknowledge a superior, and likewise states dependent upon another, can wage a defensive war under their own auspices and without the permission of the supreme magistrate. For each has no less right to defend himself and his citizens than any private person has; but anyone can arm himself against an aggressor and repel force by force.
§ 5. A prince who is under another and greater prince, or a state which obeys another, ordinarily cannot be the first to declare an offensive war against another. This may happen in two ways, for he declares war either against another prince who is a member of the same state or against a foreigner. He cannot declare war against a prince who is a citizen of the same state, because each has a judge who may decide the matter. Therefore, just as citizens recover what belongs to them not by violence and armed force but at law, so nobles, counts, and dukes ought to hear the supreme judge concerning their controversies. Otherwise the whole state would be disturbed and the stronger would oppress the weaker. The jurist Marcian answered, concerning the Julian Law of Treason, that he who waged war without the prince’s command, held a levy, or prepared an army is bound under the law of treason.
§ 6. Nor can a prince carry war against a foreign prince if the supreme magistrate does not consent, although this can be granted more readily. For if the foreigner is absolute and acknowledges no superior, he cannot summon him before his king’s tribunal, which the foreigner does not acknowledge. If the foreign prince also has a lord, he can be accused before him and can be compelled by him to give satisfaction; but if that lord is unwilling, not even then can a prince established under another attack his adversary in war without his own king’s consent.
The reason is to be sought from the very union and ordering of the members of the state among themselves, which forbids any member to be moved without the consent and will of the whole. For how great would be the losses, and how atrocious the wars, that would arise if some prince of France made war upon a prince of Spain? Would not whole kingdoms immediately be shaken? Charles the Bold declared war upon the Frenchman and moved the whole empire. A great part of wars has taken its origin from private disputes and injuries. Moreover, it is dangerous even to great kingdoms for one prince to pursue foreigners in war, to possess soldiers, and to exercise arms; he who has become accustomed to wars is easily armed against his neighbors.
§ 7. I have denied ordinary power; I grant extraordinary power. The extraordinary power is twofold. The first exists when the circumstances are such that unless war is anticipated, all will be in great danger. The second exists when the superior prince is far away, the cause and opportunity frequently coincide, and the king cannot be consulted; for then he is accustomed to commit to inferiors the right of declaring and waging war. This latter reason has no difficulty: the decision of war and peace belongs to the inferior by commission of the superior. In this way the governors of the Indies can wage war and defend allies, by the common law and power of the office they hold.
There is a difficulty concerning the former manner, for jurists and theologians deny the power of an offensive war. But I except one certain condition: when the state of affairs is such that the enemy must be forestalled. The Turkish enemies drive off booty and give cause for war. The duke to whom the frontier is committed demands the return of the property and is mocked. Meanwhile, a singular opportunity is offered to occupy a certain city which carries great weight for the war and which, if it remains in the enemy’s power, can bring Christians into great danger because arms and resources are in it. I say that he will act rightly if he uses the opportunity, for this offensive action is necessary, or certainly most useful, for his defense. Even a private person, for a defense of blameless protection, when he falls among robbers and sees that otherwise he must perish, can forestall them if he sees an opportunity.
§ 8. Against internal enemies many princes and cities have been given power to wage war without the superior’s command and knowledge. For they are subjects whom the magistrate can and ought to restrain: first by laws and the penalties of laws; but if they are more powerful than to be held by laws, they must be subdued by war. Further, there is more danger in these men unless they are quickly suppressed. Finally, no external enemy is provoked when a magistrate suppresses his own subjects; rather, he is more provoked if sedition gains strength. Particular magistrates, moreover, if they are compared with the supreme magistrate, are regarded as private persons; if compared with subjects, they are magistrates and bear the sword—not against all, but against those who are subject to them.
§ 9. If two princes contend with one another and the king, for example, neglects justice, does not aid the one who has suffered injury, but allows him to be oppressed, many think that not even then can war be undertaken by those oppressed, but that the injury must be endured. This is without doubt severe, since subjects’ bodies and possessions are vexed and carried away, and a prince can thus be stripped of all goods and even of life.
I think otherwise. If a foreign prince inflicts an atrocious injury upon a prince who is under the emperor, and the emperor does not administer justice, nor does anyone else, an offensive war can be waged. The reason appears evident to me: it is lawful to wage an offensive war when, without it, the prince or the part of the state which wages the war cannot be defended. But without such a war the prince or part of the state cannot be defended. There is an example in Julius, Julian, and others, who indeed possessed the power of waging war; nevertheless, the situation itself gives it also to one who does not possess it but is in like fortune. Every year the Germans crossed the Rhine and kept the province under attack. Merely to defend their own territory was too little a protection, either for the dignity of the empire or for the security of the subjects, for before they withdrew they always left the province afflicted by great losses. Accordingly, the Romans crossed the Rhine in turn, burned their huts, and raged with slaughter and bonds. For enemies become very insolent when they see that they are merely repelled and are without danger at home. Therefore, just as a private person, when justice is denied, can repair his loss by another compensation, so too can a prince—and indeed by a stronger right, because the defense of the people rests upon him.
§ 10. Formerly, in the Roman Empire, so vast and powerful, it was not lawful for any subject prince or king to wage war against others, much less for prefects and proconsuls to wage it against their colleagues; and when this was done, it was regarded as a civil and impious war. Nor at the present time is it permitted in either the kingdom of France or Spain, and the Pizarros, who began tumults and civil wars in the West, were deservedly punished. But now in Germany princes frequently wage wars among themselves, and did so formerly, to such a degree that some maintain it is lawful for the princes of Germany to declare war upon their colleagues without the emperor’s consent.
Concerning this matter I determine as follows. That power, if it has been given to princes, is destructive. For it is just as if, in slight ailments of the body, before fomentations and the easy services of physicians, iron and fire were applied. Moreover, that conceded right exhausts armies, princes, and cities while they fortify themselves against all their neighbors. It is indeed a sign that the emperor is not sufficiently powerful to decide and settle controversies. Experience teaches how great the losses arising from it have been, and Emperor Ferdinand explains them in the Diet of Worms in the year 1564.
But concerning the power of waging war against colleagues, which is thought to belong to princes, it is best to hear the constitutions of the Empire. The Golden Bull of Charles IV prohibits arsons, spoils, and robberies, which are customarily committed after a declaration of feud, unless that declaration was announced in the customary place three days beforehand. A declaration of feud is the renunciation of friendship and a withdrawal from it. Frederick III established in like manner, in the year 1442, that no one should inflict loss upon another unless he had first summoned him to equitable, just, and customary law; but Frederick complains that immense losses were brought upon the Empire by violation of this law. Clearer still is the constitution made in the year 1495 by Maximilian—or rather by the whole Empire, for very many princes were present in that place. I have thought fit to set those laws down here, that we may understand what has been conceded to the princes of the German Empire.
The first law reads thus:
MANDATE FOR PRESERVING THE PEACE
From the time of this proclamation, let no one, of whatever dignity, estate, or condition he may finally be, attempt to exercise hostilities against another, stir up wars, despoil, capture, attack, or besiege him. Let him do this neither by himself nor through another by furnishing assistance in his own name, nor by detaching any fortress, towns, castles, fortifications, villages, country houses, or territories, nor by taking them away by force without the other’s consent, nor by causing harm through fires and similar means. Nor let anyone be present to these transgressors with counsels or auxiliaries, receive them into his house, sustain them with provisions, or tolerate them. But if anyone wishes to implead them, let this be done only in those places and courts where causes either were formerly, or now have been, decided under the ordinance of the Imperial Chamber, or where they are to be decided.
ABOLITION OF ALL HOSTILITY
Wherefore, by royal power and the force of this edict, we have abolished all public hostility throughout the whole Empire.
PENALTY FOR DISTURBERS OF THE PEACE
And if anyone, of whatever dignity or estate, acts contrary to one or more matters mentioned in the preceding article, or at least presumes to act, by the law itself, in addition to other penalties, he shall be subject to our imperial ban. By this very act we place him under our imperial proscription in such a manner that we make his life and fortunes common to all and every person, nor shall anyone who claims them for himself be deemed to attempt anything rash. Moreover, all his written instruments, obligations, and treaties, upon which he relied, shall lose all force and validity on his part. Fiefs also, however great they may be, shall revert to their proprietor; and for as long as the transgressor survives, the proprietor shall not be bound to confer either the whole or a part of them upon him or his heirs, nor to grant participation in their fruits.
IF THE TRANSGRESSORS ARE CONCEALED, AND SOMEONE IS SUSPECTED
But if the electors, princes, prelates, counts, barons, nobles, cities, or anyone else of whatever estate, dignity, or condition, whether ecclesiastical or secular, and their subjects and associates, have suffered any loss contrary to this peace; and if the transgressor is not manifest but someone is brought under suspicion, while the accusers also do not undertake to convict him, yet do not nourish suspicion from a frivolous report, let it be permitted to the injured parties to appoint a day for the suspect and to demand a clearing of himself confirmed by oath. But if the suspect refuses such a clearing in any way or does not appear on the appointed day, he shall be judged guilty of inflicting the loss and shall be visited with the aforesaid penalties of a disturber of the peace. Nevertheless, an elector, prince, prelate, count, baron, noble, or city must provide the other person, and those who will be in his company, with safe-conduct until he is placed in safety. And if perhaps the letters by which the day is assigned and appointed cannot be delivered to him, it will be necessary to affix and publish them in two or three places where he is thought likely to transact business. And if, indeed, contrary to this mandate of ours, anyone has been despoiled, injured, or affected by another loss, then those who are notified of the matter after the recent crime has been committed, or learn of it in another way, shall pursue the perpetrators with all force, zeal, and diligence, and shall seek them out as though the loss had been inflicted upon themselves.
DISTURBERS OF THE PEACE ARE NOT TO BE RECEIVED INTO ONE’S HOUSE
Nor shall anyone receive transgressors of this kind into his house, or furnish them food and assistance in those places which belong to his superior, or even in his own jurisdictions; rather, he shall detain them and shall seriously take cognizance of their causes even upon the accusation of any person. Nor is there any security, safe-conduct, or privilege which such men may allege, since they are in no way capable of any of these without the consent of the opposing party. For in all privileges and safe-conducts which we have granted, we will that this disturbance of the peace be excepted.
CONCERNING PROTECTION AGAINST DISTURBERS OF THE PEACE
If perhaps these transgressors and disturbers of the peace employ so great a defense, assistance, other aids, and favor that there would be need of a proper army and of leading it into the field; or if anyone comprehended in this general peace, of whatever estate, dignity, and condition he may be, whether ecclesiastical or secular—or anyone not comprehended in it—has been defamed, accused, or affected by some loss, or even fosters and assists these transgressors, let this be referred by the injured parties or by the judges of the Imperial Chamber to us, or to our legate, and to the annual assembly of the electors, princes, and estates of the Empire. There assistance shall be decreed for the injured party without any delay.
But if it should happen, on account of some invasion or incursion, that that annual assembly cannot be awaited, we give power both to the judge of our Imperial Chamber in our name and to the electors, princes, and estates of the Empire to select some convenient and suitable place to which both we and they, or our and their legates, may come even by force and determine the matter as has been said. Nevertheless, it shall always be lawful for the judgment of our Imperial Chamber, and incumbent upon it, to proceed by law against the guilty, either by virtue of its office or upon the complaints and petitions of the injured parties.
IF ECCLESIASTICAL PERSONS ATTEMPT ANYTHING AGAINST THIS PEACE
If ecclesiastical persons—which we shall never expect—attempt anything against this peace, the prelates who possess immediate judicial power over them shall, at the petition and requisition of the injured parties and without any evasion, exact restoration in full of the losses so far as it can be done, and the guilty themselves shall be heavily fined. And if the prelates are negligent and do not exact penalties from the guilty, we deprive these prelates, just as we do the guilty, of all our favor and that of the Empire, and of grace and protection, as violators of the peace; nor let them hope for any assistance from us in adversity. Nevertheless, a clearing of themselves, as has also been said concerning secular persons, shall not be denied them if there is merely suspicion.
Moreover, during the peace no one shall be bound by any written instruments and treaties against this peace; for by the force and virtue of our royal preeminence we make and declare them all null and void. This, however, insofar as it concerns the remaining provisions of such written instruments and treaties, shall affect nothing at all; nor shall this public and universal peace and quiet of the whole Empire alter anything in other honest and lawful obligations of debts.
THOSE WHO ARE PROSCRIBED FOR DISTURBING THE PEACE
But those who have been proscribed for these offenses shall by no means be absolved by us without the consent and will of the injured parties, unless the law has awarded the cause to them. Hence, by royal power, we also command all and every one of you mentioned above, in accordance with the oaths and obligations made to us particularly for the sake of the Empire, and also the obedience which you promised us as King of the Romans, to observe this prescribed peace and our mandate with all its points, articles, and clauses as steadfastly as possible, unless any of you wishes to incur the loss of all our grace, and of the privileges and rights which have come to you either from us and the Holy Empire or from others. Moreover, throughout your principalities, counties, and dominions, and whatever is finally subject to the jurisdiction of each, we command you to strive, together with all your officials and subjects, by whatever name they may be called, to preserve and advance this established peace, and not in any way to attempt anything against it, whereby you would deserve both the penalties established against transgressors and our displeasure.
ABOLITION OF ALL PRIVILEGES WHICH CAN BE AGAINST THIS UNIVERSAL PEACE
We also set aside and reject all privileges, safe-conducts, customs, and treaties granted by us or our predecessors which can in any way be opposed to this peace, by whatever words, clauses, or intentions they may have been granted. By royal authority and power we declare them all annulled and void, nor do we will that anyone, of whatever dignity, estate, or condition, allege any defense through these privileges, customs, and treaties in any way.
THIS PEACE SHALL PREJUDICE NO OTHER RIGHTS
Nor shall this peace and our edict result in any prejudice, but rather in an increase, to our universal law and that of the Holy Empire, and to other ordinances and mandates issued before this; and absolutely everyone shall be bound to preserve it from the first moment of its promulgation.
These matters were explained more clearly at Augsburg in the year 1500. In the year 1512, however, at Cologne, a league was entered into among the princes and a method established by which violators of the peace could be corrected and punished. The same things were repeated in the same order in the year 1521 by Charles V. These were confirmed in subsequent years: in the year 1522 at Nuremberg; in the year 1526 at Speyer; in the year 1530 at Augsburg; in the year 1542 at Speyer, and in the same year at Nuremberg; in the year 1544 at Speyer; in the year 1545 at Worms; in the years 1566 and 1567 at Regensburg; in the year 1548 at Augsburg, and there in 1551, 1555, and 1559; in the year 1564 at Worms; and in the year 1570 at Speyer. These things were also enacted in other assemblies, but were by no means observed, as the whole Empire complained to Emperor Ferdinand in the year 1564.
Accordingly, an offense against the laws is always committed when an offensive war is undertaken, if it can be avoided, when it is possible to obtain one’s cause through the laws. Therefore there remains what was also formerly provided by laws: that to prepare arms, collect money, enroll an army, and invade others is the crime of treason. See Paul in the law amissione.
§ 11. When war is waged without the prince’s authority, both those who inflicted the losses and their heirs must make the losses good. For although the cause was legitimate, they nevertheless had no right to affect others with such great injuries. Thus it is not lawful for a private person to punish a thief, although caught in the crime, but he must be delivered to the magistrate. Yet they can recover their own property without an obligation to restore it, although not without sin, unless, having pursued the enemies without interruption, they subdue them. Further, if the enemies inflicted harm, they ought not to repair their own losses from spoil taken without the prince’s authority; nevertheless, if they have done so, they are not bound to restore it unless the enemies give satisfaction.
§ 12. Tribunes, centurions, and soldiers ought not to attack an enemy on their own authority, nor to rage with arsons and devastations, unless power has been granted by the prince, either specially or generally, to harm the enemy in every way they can. Therefore, they sin gravely when, against the commander’s will, they set fire to hostile fields, villages, and towns. For they are not judges but executors of justice, and no more is lawful for them than has been permitted. Thus a soldier who kills an enemy to whom the commander granted life is a murderer, and one who burns a city against the prince’s will is an incendiary and is obligated to make good the loss; for a minister of justice cannot rage beyond the measure prescribed by the magistrate.
Formerly commands were so regarded that a soldier could not move his arms without his commander’s order. It is the law of Modestinus: “He who in war has done a thing prohibited by the commander, or has not observed his orders, is punished capitally, even if he has conducted the affair well.” For this reason Manlius and Postumius were cruel to their own sons. And just as it is a capital crime not to hand over an army to one’s successor, or to retain it by force and against the magistrate’s will, so too it is a capital crime to fight against the magistrate’s will. When challenged by a Gaul, Titus Manlius addresses the dictator nobly: “Commander, without your order I shall not fight outside the ranks, not even if I should perceive certain victory. If you permit it, I shall meet the challenge.” The reason is that which has already been explained above, and great disadvantages would follow: for anyone could kill a private enemy as though he were a public enemy.