The Law of Nations or the Principles of Natural Law (1758)

Emmerich de Vattel

Of the Just Causes of War

§ 24. War never to be undertaken without very cogent reasons.
WHOEVER entertains a true idea of war, — whoever considers its terrible effects, its destructive and unhappy consequences, will readily agree that it should never be undertaken without the most cogent reasons. Humanity revolts against a sovereign, who, without necessity or without very powerful reasons, lavished the blood of his most faithful subjects, and exposes his people to the calamities of war, when he has it in his power to maintain them in the enjoyment of an honorable and salutary peace. And if to this imprudence, this want of love for his people, he moreover adds injustice towards those he attacks, — of how great a crime, or rather, of what a frightful scries of crimes, does he not become guilty! Responsible for all the misfortunes which ho draws down on his own subjects, he is moreover loaded with the guilt of all those which he inflicts on an innocent nation. The slaughter of men, the pillage of cities, the devastation of provinces, — such is the black catalogue of his enormities. He is responsible to God, and accountable to human nature, for every individual that is killed, for every hut that is burned down. The violences, the crimes, the disorders of every kind, attendant on the tumult and licentiousness of war, pollute his conscience, and are set down to his account, as he is the original author of them all. Unquestionable truths! alarming ideas!! which ought to affect the rulers of nations, and, in all their military enterprises, inspire them with a degree of circumspection proportionate to the importance of the subject!

§ 25. Justificatory reasons, and motives for making war.
Were men always reasonable, they would terminate their contests by the arms of reason only; natural justice and equity would be their rule, or their judge. Force is a wretched and melancholy expedient against those who spurn at justice, and refuse to listen to the remonstrances of reason: but, in short, it becomes necessary to adopt that mode, when every other proves ineffectual. It is only in extremities that a just and wise nation, or a good prince, has recourse to it, as we have shown in the concluding chapter of the second book. The reasons which may determine him to take such a step are of two classes. Those of the one class show that he has a right to make war, — that he has just grounds for undertaking it: — these are called justificatory reasons. The others, founded on fitness and utility, determine whether it be expedient for the sovereign to undertake a war, — these are called motives.

§ 26. What is in general a just cause of war.
The right of employing force, or making war, belongs to nations no farther than is necessary for their own defense, and for the maintenance of their rights (§ 3). Now, if any one attacks a nation, or violates her perfect rights, he does her an injury. Then, and not till then, that nation has a right to repel the aggressor, and reduce him to reason. Further, she has a right to prevent the intended injury, when she sees herself threatened with it (Book II. § 50). Let us then say in general, that the foundation, or cause of every just war is injury, either already done or threatened. The justificatory reasons for war show that an injury has been received, or so far threatened as to authorize a prevention of it by arms. It is evident, however, that here the question regards the principal in the war, and not those who join in it as auxiliaries. When, therefore, we would judge whether a war be just, we must consider whether he who undertakes it has in fact received an injury, or whether he be really threatened with one. And, in order to determine what is to be considered as an injury, we must be acquainted with a nation’s rights, properly so called, — that is to say, her perfect rights. These are of various kinds, and very numerous, but may all be referred to the general heads of which we have already treated, and shall further treat in the course of this work. Whatever strikes at these rights is an injury, and a just cause of war.

§ 27. What war is unjust.
The immediate consequence of the premises is, that if a nation takes up arms when she has received no injury, nor is threatened with any, she undertakes an unjust war. Those alone, to whom an injury is done or intended, have a right to make war.

§ 28. The object of war.
From the same principle we shall likewise deduce the just and lawful object of every war, which is, to avenge or prevent injury. To avenge signifies here to prosecute the reparation of an injury, if it be of a nature to be repaired, — or, if the evil be irreparable, to obtain a just satisfaction, — and also to punish the offender, if requisite, with a view of providing for our future safety. The right to security authorizes us to do all this (Book II. §§ 49-52). We may therefore distinctly point out, as objects of a lawful war, the three following: — 1. To recover what belongs, or is due to us. 2. To provide for our future safety by punishing the aggressor or offender. 3. To defend ourselves, or to protect ourselves from injury, by repelling unjust violence. The two first are the objects of an offensive, the third of a defensive war. Camillus, when on the point of attacking the Gauls, concisely set forth to his soldiers all the subjects on which war can be grounded or justified — omnia, quæ defendi, repetique, et ulcisci fas sit.2

§ 29. Both justificatory reasons and proper motives requisite in undertaking a war.
As the nation, or her ruler, ought, in every undertaking, not only to respect justice, but also to keep in view the advantage of the state, it is necessary that proper and commendable motives should concur with the justificatory reasons, to induce a determination to embark in a war. These reasons show that the sovereign has a right to take up arms, that he has just cause to do so. The proper motives show, that in the present case it is advisable and expedient to make use of his right. These latter relate to prudence, as the justificatory reasons come under the head of justice.

§ 30. Proper motives.
I call proper and commendable motives those derived from the good of the state, from the safety and common advantage of the citizens. They are inseparable from the justificatory reasons, — a breach of justice being never truly advantageous. Though an unjust war may for a time enrich a state, and extend her frontiers, it renders her odious to other nations, and exposes her to the danger of being crushed by them. Besides, do opulence and extent of dominion always constitute the happiness of states? Amidst the multitude of examples which might here be quoted, let us confine our view to that of the Romans. The Roman republic ruined herself by her triumphs, by the excess of her conquests and power. Rome, when mistress of the world, but enslaved by tyrants and oppressed by a military government, had reason to deplore the success of her arms, and to look back with regret on those happy times when her power did not extend beyond the bounds of Italy, or even when her dominion was almost confined within the circuit of her walls.

Vicious motives are those which have not for their object the good of the state, and which, instead of being drawn from that pure source, are suggested by the violence of the passions. Such are the arrogant desire of command, the ostentation of power, the thirst of riches, the avidity of conquest, hatred, and revenge.

§ 31. War undertaken upon just grounds, but from vicious motives.
The whole right of the nation, and consequently of the sovereign, is derived from the welfare of the state; and by this rule it is to be measured. The obligation to promote and maintain the true welfare of the society or state gives the nation a right to take up arms against him who threatens or attacks that valuable enjoyment. But if a nation, on an injury done to her, is induced to take up arms, not by the necessity of procuring a just reparation, but by a vicious motive, she abuses her right. The viciousness of the motive tarnishes the luster of her arms, which might otherwise have shone in the cause of justice: — the war is not undertaken for the lawful cause which the nation had to engage in it: that cause is now no more than a pretext. As to the sovereign in particular, the ruler of the nation — what right has he to expose the safety of the state, with the lives and fortunes of the citizens, to gratify his passions? It is only for the good of the nation that the supreme power is intrusted to him; and it is with that view that he ought to exert it: that is the object prescribed to him even in his least important measures: and shall he undertake the most important and the most dangerous, from motives foreign or contrary to that great end? Yet nothing is more common that such a destructive inversion of views; and it is remarkable, that, on this account, the judicious Polybius gives the name of causes3 to the motives on which war is undertaken, — and of pretexts4 to the justificatory reasons alleged in defense of it. Thus he informs us that the cause of the war which Greece undertook against the Persians was the experience she had had of their weakness, and that the pretext alleged by Philip, or by Alexander after him, was the desire of avenging the injuries which the Greeks had so often suffered, and of providing for their future safety.

§ 32. Pretexts.
Let us, however, entertain a better opinion of nations and their rulers. There are just causes of war, real justificatory reasons; and why should there not be sovereigns who sincerely consider them as their warrant, then they have besides reasonable motives for taking up arms? We shall therefore give the name of pretexts to those reasons alleged as justificatory, but which are so only in appearance, or which are even absolutely destitute of all foundation. The name of pretexts may likewise be applied to reasons which are, in themselves, true and well-founded, but, not being of sufficient importance for undertaking a war, are made use of only to cover ambitious views, or some other vicious motive. Such was the complaint of the czar Peter I. that sufficient honors had not been paid him on his passage through Riga. His other reasons for declaring war against Sweden I here omit.

Pretexts are at least a homage which unjust men pay to justice. He who screens himself with them shows that he still retains some sense of shame. He does not openly trample on what is most sacred in human society: he tacitly acknowledges that a flagrant injustice merits the indignation of all mankind.

§ 33. War undertaken merely for advantage.
Whoever, without justificatory reasons, undertakes a war merely from motives of advantage, acts without any right, and his war is unjust. And he, who, having in reality just grounds for taking up arms, is nevertheless solely actuated by interested views in resorting to hostilities, cannot indeed be charged with injustice, but he betrays a vicious disposition: his conduct is reprehensible, and sullied by the badness of his motives. War is so dreadful a scourge, that nothing less than manifest justice, joined to a kind of necessity, can authorize it, render it commendable, or at least exempt it from reproach,

§ 34. Nations who make war without reason or apparent motives.
Nations that are always ready to take up arms on any prospect of advantage, are lawless robbers: but those who seem to delight in the ravages of war, who spread it on all sides, without reasons or pretexts, and even without any other motive than their own ferocity, are monsters, unworthy the name of men. They should be considered as enemies to the human race, in the same manner as, in civil society, professed assassins and incendiaries are guilty, not only towards the particular victims of their nefarious deeds, but also towards the state, which therefore proclaims them public enemies. All nations have a right to join in a confederacy for the purpose of punishing and even exterminating those savage nations. Such were several German tribes mentioned by Tacitus — such those barbarians who destroyed the Roman empire: nor was it till long after their conversion to Christianity that this ferocity wore off. Such have been the Turks and other Tartars — Genghis Khan, Timur Bec or Tamerlane, who, like Attila, were scourges employed by the wrath of Heaven, and who made war only for the pleasure of making it. Such are, in polished ages and among the most civilized nations, those supposed heroes, whose supreme delight is a battle, and who make war from inclination purely, and not from love to their country.

§ 35. How defensive war is just or unjust.
Defensive war is just when made against an unjust aggressor. This requires no proof. Self-defense against unjust violence is not only the right, but the duty of a nation, and one of her most sacred duties. But if the enemy who wages offensive war has justice on his side, we have no right to make forcible opposition; and the defensive war then becomes unjust: for that enemy only exerts his lawful right: — he took arms only to obtain justice which was refused to him; and it is an act of injustice to resist any one in the exertion of his right.

§ 36. How it may become just against an offensive war which at first was just.
All that remains to be done in such a case is, to offer the invader a just satisfaction. If he will not be content with this, a nation gains one great advantage — that of having turned the balance of justice on her own side; and his hostilities, now becoming unjust, as having no longer any foundation, may very justly be opposed.

The Samnites, instigated by the ambition of their chiefs, had ravaged the lands of the allies of Rome. When they became sensible of their misconduct, they offered full reparation for the damages, with every reasonable satisfaction: but all their submissions could not appease the Romans; whereupon Caius Pontius, general of the Samnites, said to his men, “Since the Romans are absolutely determined on war, necessity justifies it on our side; an appeal to arms becomes lawful on the part of those who are deprived of every other resource.” — Justum est bellum, quibus necessarium; et pia arma, quibus nulla nisi in armis relinquitur spes.5

§ 37. How an offensive war is just in an evident cause.
In order to estimate the justice of an offensive war, the nature of the subject for which a nation takes up arms must be first considered. We should be thoroughly assured of our right, before we proceed to assert it in so dreadful a manner. If, therefore, the question relates to a thing which is evidently just, as the recovery of our property, the assertion of a clear and incontestable right, or the attainment of just satisfaction for a manifest injury, and if we cannot obtain justice otherwise than by force of arms, offensive war becomes lawful. Two things are therefore necessary to render it just: 1, some right which is to be asserted — that is to say, that we be authorized to demand something of another nation: 2, that we be unable to obtain it otherwise than by force of arms, Necessity alone warrants the use of force. It is a dangerous and terrible resource. Nature, the common parent of mankind, allows of it only in cases of the last extremity, and when all other means fail. It is doing wrong to a nation, to make use of violence against her, before we know whether she be disposed to do us justice, or to refuse it.

Those who without trying pacific measures, run to arms on every trifling occasion, sufficiently show that justificatory reasons are, in their mouths, mere pretexts: they eagerly seize the opportunity of indulging their passions and gratifying their ambition under some color of right.

§ 38. In a doubtful cause.
In a doubtful cause, where the rights are uncertain, obscure and disputable, all that can be reasonably required is, that the question be discussed (Book II. § 331), and that, if it be impossible fully to clear it up, the contest be terminated by an equitable compromise. If, therefore, one of the parties should refuse to accede to such conciliatory measures, the other is justifiable in taking up arms to compel him to an accommodation. And we must observe, that war does not decide the question: victory only compels the vanquished to subscribe to the treaty which terminates the difference. It is an error, no less absurd than pernicious, to say that war is to decide controversies between those who acknowledge no superior judge — as is the case with nations. Victory usually favors the cause of strength and prudence, rather than that of right and justice. It would be a bad rule of decision; but it is an effectual mode of compelling him who refuses to accede to such measures as are consonant to justice; and it becomes just in the hands of a prince who uses it seasonably, and for a lawful cause.

§ 39. War cannot be just on both sides.
War cannot be just on both sides. One party claims a right; the other disputes it: the one complains of an injury: the other denies having done it. They may be considered as two individuals disputing on the truth of a proposition; and it is impossible that two contrary sentiments should be true at the same time.

§ 40. Sometimes reputed lawful.
It may however happen that both the contending parties are candid and sincere in their intentions; and, in a doubtful cause, it is still uncertain which side is in the right. Wherefore, since nations are equal and independent (Book II. § 36, and Prelim. §§ 18, 19), and cannot claim a right of judgment over each other, it follows, that in every case susceptible of doubt, the arms of the two parties at war are to be accounted equally lawful, at least as to external effects, and until the decision of the cause. But neither does that circumstance deprive other nations of the liberty of forming their own judgment on the case, in order to determine how they are to act, and to assist that party who shall appear to have right on his side; nor does that effect of the independence of nations operate in exculpation of the author of an unjust war, who certainly incurs a high degree of guilt. But if he acts in consequence of invincible ignorance or error, the injustice of his arms is not imputable to him.

§ 41. War undertaken to punish a nation.
When offensive war has for its object the punishment of a nation, it ought, like every other war, to be founded on right and necessity. 1. On right: — an injury must have been actually received. Injury alone being a just cause of war (§ 26), the reparation of it may be lawfully prosecuted: or if, in its nature, it be irreparable (the only case in which we are allowed to punish), we are authorized to provide for our own safety, and even for that of all other nations, by inflicting on the offender a punishment capable of correcting him, and serving as an example to others. 2. A war of this kind must have necessity to justify it; that is to say, that, to be lawful, it must be the only remaining mode to obtain a just satisfaction; which implies a reasonable security for the time to come. If that complete satisfaction, be offered, or if it may be obtained without a war, the injury is done away, and the right to security no longer authorizes us to seek vengeance for it. — (See Book II. §§ 49, 52.)

The nation in fault is bound to submit to a punishment which she has deserved, and to suffer it by way atonement: but she is not obliged to give herself up to the discretion of an incensed enemy. Therefore, when attacked she ought to make a tender of satisfaction, and ask what penalty is required; and if no explicit answer be given, or the adversary attempts to impose a disproportionate penalty, she then acquires a right to resist, and her defense becomes lawful.

On the whole, however, it is evident that the offended party alone has a right to punish independent persons. We shall not here repeat what we have said elsewhere (Book II. § 7) of the dangerous mistake, or extravagant pretensions, of those who assume a right of punishing an independent nation for faults which do not concern them — who, madly setting themselves up as defenders of the cause of God, take upon them to punish the moral depravity, or irreligion, of a people not committed to their superintendency.

§ 42. Whether the aggrandizement of a neighboring power can authorize a war against him.
Here a very celebrated question, and of the highest importance, presents itself. It is asked, whether the aggrandizement of a neighboring power, by whom a nation fears she may one day be crushed, be a sufficient reason for making war against him — whether she be justifiable in taking up arms to oppose his aggrandizement, or to weaken him, with the sole view of securing herself from those dangers which the weaker states have almost always reason to apprehend from an overgrown power. To the majority of politicians this question is no problem: it is more difficult of solution to those who wish to see justice and prudence ever inseparably united.

On the one hand, a state that increases her power by all the arts of good government, does no more than what is commendable — she fulfills her duties towards herself without violating those which she owes to other nations. The sovereign, who, by inheritance, by free election, or by any other just and honorable means, enlarges his dominions by the addition of new provinces or entire kingdoms, only makes use of his right, without injuring any person. How then should it be lawful to attack a state which, for its aggrandizement, makes use only of lawful means? We must either have actually suffered an injury or be visibly threatened with one, before we are authorized to take up arms, or have just grounds for making war (§§ 26, 27). On the other hand, it is but too well known, from sad and uniform experience, that predominating powers seldom fail to molest their neighbors, to oppress them, and even totally subjugate them, whenever an opportunity occurs, and they can do it with impunity. Europe was on the point of falling into servitude for want of a timely opposition to the growing fortune of Charles V. Is the danger to be waited for? Is the storm, which might be dispersed at its rising, to be permitted to increase? Are we to allow of the aggrandizement of a neighbor, and quietly wait till he makes his preparations to enslave us? Will it be a time to defend ourselves when we are deprived of the means? Prudence is a duty incumbent on all men, and most pointedly so on the heads of nations, as being commissioned to watch over the safety of a whole people. Let us endeavor to solve this momentous question, agreeably to the sacred principles of the law of nature and of nations. We shall find that they do not lead to weak scruples, and that it is an invariable truth that justice is inseparable from sound policy.

§ 43. Alone and of itself, it cannot give a right to attack him.
And first, let us observe, that prudence, which is, no doubt, a virtue highly necessary in sovereigns, can never recommend the use of unlawful means for the attainment of a just and laudable end. Let not the safety of the people, that supreme law of the state, be alleged here in objection; for the very safety of the people itself, and the common safety of nations, prohibit the use of means which are repugnant to justice and probity. Why are certain means unlawful? If we closely consider the point, if we trace it to its first principles, we shall see that it is purely because the introduction of them would be pernicious to human society, and productive of fatal consequences to all nations.

See particularly what we have said concerning the observance of justice (Book II. Chap. V.). For the interest, therefore, and even the safety of nations, we ought to hold it as a sacred maxim, that the end does not sanctify the means. And since war is not justifiable on any other ground than that of avenging an injury received, or preserving ourselves from one with which we are threatened (§ 26), it is a sacred principle of the law of nations, that an increase of power cannot, alone and of itself, give any one a right to take up arms in order to oppose it.

§ 44. How the appearances of danger give that right.
No injury has been received from that power (so the question supposes); we must, therefore, have good grounds to think ourselves threatened by him, before we can lawfully have recourse to arms. Now power alone does not threaten an injury: — it must be accompanied by the will. It is, indeed, very unfortunate for mankind, that the will and inclination to oppress may be almost always supposed, where there is a power of oppressing with impunity. But these two things are not necessarily inseparable: and the only right which we derive from the circumstance of their being generally or frequently united, is, that of taking the first appearances for a sufficient indication. When once a state has given proofs of injustice, rapacity, pride, ambition, or an imperious thirst of rule, she becomes an object of suspicion to her neighbors, whose duty it is to stand on their guard against her. They may come upon her at the moment when she is on the point of acquiring a formidable accession of power, — may demand securities, — and if she hesitates to give them, may prevent her designs by force of arms. The interests of nations are, in point of importance, widely different from those of individuals: the sovereign must not be remiss in his attention to them, nor suffer his generosity and greatness of soul to supersede his suspicions. A nation that has a neighbor at once powerful and ambitious has her all at stake. As men are under a necessity of regulating their conduct in most cases by probabilities, those probabilities claim their attention in proportion to the importance of the subject: and (to make use of a geometrical expression) their right to obviate a danger is in a compound ratio of the degree of probability and the greatness of the evil threatened. If the evil in question be of a supportable nature, — if it be only some slight loss, — matters are not to be precipitated: there is no great danger in delaying our opposition to it till there be a certainty of our being threatened. But if the safety of the state lies at stake, our precaution and foresight cannot be extended too far. Must we delay to avert our ruin till it is become inevitable? If the appearances are so easily credited, it is the fault of that neighbor who has betrayed his ambition by several indications. If Charles the Second, King of Spain, instead of settling the succession on the Duke of Anjou, had appointed for his heir Louis XIV. himself — to have tamely suffered the union of the monarchy of Spain with that of France, would, according to all the rules of human foresight, have been nothing less than delivering up all Europe to servitude, or at least reducing it to the most critical and precarious situation. But then, if two independent nations think fit to unite, so as afterwards to form one joint empire, have they not a right to do it? And who is authorized to oppose them? I answer, they have a right to form such a union, provided the views by which they are actuated be not prejudicial to other states. Now, if each of the two nations in question be, separately and without assistance, able to govern and support herself, and to defend herself from insult and oppression, it may be reasonably presumed that the object of their coalition is to domineer over their neighbors. And, on occasions where it is impossible or too dangerous to wait for an absolute certainty, we may justly act on a reasonable presumption. If a stranger levels a musket at me in the middle of a forest, I am not yet certain that he intends to kill me; but shall I, in order to be convinced of his design, allow him time to fire? What reasonable casuist will deny me the right to anticipate him? But presumption becomes nearly equivalent to certainty, if the prince who is on the point of rising to an enormous power has already given proofs of imperious pride and insatiable ambition. In the preceding supposition, who could have advised the powers of Europe to suffer such a formidable accession to the power of Louis the Fourteenth? Too certain of the use he would have made of it, they would have joined in opposing it: and in this their safety warranted them. To say that they should have allowed him time to establish his dominion over Spain, and consolidate the union of the two monarchies, — and that, for fear of doing him an injury, they should have quietly waited till he crushed them all, — would not this be, in fact, depriving mankind of the right to regulate their conduct by the dictates of prudence, and to act on the ground of probability? Would it not be robbing them of the liberty to provide for their own safety, as long as they have not mathematical demonstration of its being in danger? It would have been in vain to have preached such a doctrine. The principal sovereigns of Europe, habituated, by the administration of Louvois, to dread the views and power of Louis XIV., carried their mistrust so far, that they would not even suffer a prince of the house of France to sit on the throne of Spain, though invited to it by the nation, whose approbation had sanctioned the will of her former sovereign. He ascended it, however, notwithstanding the efforts of those who so strongly dreaded his elevation; and it has since appeared that their policy was too suspicious.

§ 45. Another case more evident.
It is still easier to prove, that, should that formidable power betray an unjust and ambitious disposition, by doing the least injustice to another, all nations may avail themselves of the occasion, and, by joining the injured party, thus form a coalition of strength, in order to humble that ambitious potentate, and disable him from so easily oppressing his neighbors, or keeping them in continual awe and fear. For an injury gives us a right to provide for our future safety, by depriving the unjust aggressor of the means of injuring us; and it is lawful and even praiseworthy to assist those who are oppressed, or unjustly attacked.

Enough has been said on this subject, to set the minds of politicians at case, and relieve them from all apprehension that a strict and punctilious observance of justice in this particular would pave the way to slavery. It is perhaps wholly unprecedented that a state should receive any remarkable accession of power, without giving other states just causes of complaint. Let the other nations be watchful and alert in repressing that growing power, and they will have nothing to fear. The emperor Charles V. laid hold on the pretext of religion, in order to oppress the princes of the empire, and subject them to his absolute authority. If, by following up his victory over the elector of Saxony, he had accomplished that vast design, the liberties of all Europe would have been endangered. It was therefore with good reason that France assisted the protestants of Germany: — the care of her own safety authorized and urged her to the measure. When the same prince seized on the duchy of Milan, the sovereigns of Europe ought to have assisted France in contending with him for the possession of it, and to have taken advantage of the circumstance, in order to reduce his power within just bounds. Had they prudently availed themselves of the just causes which he soon gave them to form a league against him, they would have saved themselves the subsequent anxieties for their tottering liberty.

§ 46. Other allowable means of defense against a formidable power.
But, suppose that powerful state, by the justice and circumspection of her conduct, affords us no room to take exception to her proceedings, are we to view her progress with an eye of indifference? Are we to remain quiet spectators of the rapid increase of her power, and imprudently expose ourselves to such designs as it may inspire her with? — No, beyond all doubt. In a matter of so high importance, imprudent supineness would be unpardonable. The example of the Romans is a good lesson for all sovereigns. Had the potentates of those times concerted together to keep a watchful eye on the enterprises of Rome, and to check her incroachments, they would not have successively fallen into servitude. But force of arms is not the only expedient by which we may guard against a formidable power. There are other means, of a gentler nature, and which are at all times lawful. The most effectual is a confederacy of the less powerful sovereigns, who, by this coalition of strength, become able to hold the balance against that potentate whose power excites their alarms. Let them be firm and faithful in their alliance; and their union will prove the safety of each.

They may also mutually favor each other, to the exclusion of him whom they fear; and by reciprocally allowing various advantages to the subjects of the allies, especially in trade, and refusing them to those of that dangerous potentate, they will augment their own strength, and diminish his, without affording him any just cause of complaint, since every one is at liberty to grant favors and indulgences at his own pleasure.

§ 47. Political equilibrium.
Europe forms a political system, an integral body, closely connected by the relations and different interests of the nations inhabiting this part of the world. It is not, as formerly, a confused heap of detached pieces, each of which though herself very little concerned in the fate of the others, and seldom regarded things which did not immediately concern her. The continual attention of sovereigns to every occurrence, the constant residence of ministers, and the perpetual negotiations, make of modern Europe a kind of republic, of which the members — each independent, but all linked together by the ties of common interest — unite for the maintenance of order and liberty. Hence arose that famous scheme of the political balance, or the equilibrium of power; by which is understood such a disposition of things, as that no one potentate be able absolutely to predominate, and prescribe laws to the others.

§ 48. Ways of maintaining it.
The surest means of preserving that equilibrium would be, that no power should be much superior to the others, that all, or at least the greater part, should be nearly equal in force. Such a project has been attributed to Henry the Fourth:6 but it would have been impossible to carry it into execution without injustice and violence. Besides, suppose such equality once established, how could it always be maintained by lawful means? Commerce, industry, military pre-eminence, would soon put an end to it. The right of inheritance, vesting even in women and their descendants, — a rule, which it was so absurd to establish in the case of sovereignties, but which nevertheless is established, — would completely overturn the whole system.

It is a more simple, an easier, and a more equitable plan, to have recourse to the method just mentioned, of forming confederacies in order to oppose the more powerful potentate, and prevent him from giving law to his neighbors. Such is the mode at present pursued by the sovereigns of Europe. They consider the two principal powers, which, on that very account, are naturally rivals, as destined to be checks on each other; and they unite with the weaker, like so many weights thrown into the lighter scale, in order to keep it in equilibrium with the other. The house of Austria has long been the preponderating power: at present France is so in her turn. England, whose opulence and formidable fleets have a powerful influence, without alarming any state on the score of its liberty, because that nation seems cured of the rage for conquest, — England, I say, has the glory of holding the political balance. She is attentive to preserve it in equilibrium: — a system of policy, which is in itself highly just and wise, and will ever entitle her to praise, as long as she continues to pursue it only by means of alliances, confederacies, and other methods equally lawful.

§ 49. How he who destroys the equilibrium may be restrained, or even weakened.
Confederacies would be a sure mode of preserving the equilibrium, and thus maintaining the liberty of nations, did all princes thoroughly understand their true interests, and make the welfare of the state serve as the rule in all their proceedings. Great potentates, however, are but too successful in gaining over partisans and allies, who blindly adopt all their views. Dazzled by the glare of a present advantage, seduced by their avarice, deceived by faithless ministers — how many princes become the tools of a power which will one day swallow up either themselves or their successors! The safest plan, therefore, is to seize the first favorable opportunity, when we can, consistently with justice, weaken the potentate who destroys the equilibrium (§ 45) — or to employ every honorable means to prevent his acquiring too formidable a degree of power. For the purpose, all the other nations should be particularly attentive not to suffer him to aggrandize himself by arms: and this they may at all times do with justice. For, if this prince makes an unjust war, every one has a right to succor the oppressed party. If he makes a just war, the neutral nations may interfere as mediators for an accommodation — they may induce the weaker state to propose reasonable terms and offer a fair satisfaction, and may save her from falling under the yoke of a conqueror. On the offer of equitable conditions to the prince who wages even the most justifiable war, he has all that he can demand. The justice of his cause, as we shall soon see, never gives him a right to subjugate his enemy, unless when that extremity becomes necessary to his own safety, or when he has no other mode of obtaining indemnification for the injury he has received. Now, that is not the case here, as the interposing nations can by other means procure him a just indemnification, and an assurance of safety.

In fine, there cannot exist a doubt, that, if that formidable potentate certainly entertain designs of oppression and conquest, — if he betray his views by his preparations and other proceedings, — the other states have a right to anticipate him; and if the fate or war declares in their favor, they are justifiable in taking advantage of this happy opportunity to weaken and reduce a power too contrary to the equilibrium, and dangerous to the common liberty.

This right of nations is still more evident against a sovereign, who, from an habitual propensity to take up arms without reasons, or even so much as plausible pretexts, is continually disturbing the public tranquillity.

§ 50. Behavior allowable towards a neighbor preparing for war.
This leads us to a particular question, nearly allied to the preceding. When a neighbor, in the midst of a profound peace, erects fortresses on our frontier, equips a fleet, augments his troops, assembles a powerful army, fills his magazines, — in a word when he makes preparations for war, — are we allowed to attack him, with a view to prevent the danger with which we think ourselves threatened? The answer greatly depends on the manner and character of that neighbor. We must inquire into the reasons of those preparations, and bring him to an explanation: — such is the mode of proceeding in Europe: and if his sincerity be justly suspected, securities may be required of him. His refusal in this case, would furnish ample indication of sinister designs, and a sufficient reason to justify us in anticipating them. But if that sovereign has never betrayed any symptoms of baseness and perfidy, and especially if at that time there is no dispute subsisting between him and us, why should we not quietly rest on his word, only taking such precautions as prudence renders indispensable? We ought not, without sufficient cause, to presume him capable of exposing himself to infamy by adding perfidy to violence. As long as he has not rendered his sincerity questionable, we have no right to require any other security from him.

It is true, however, that, if a sovereign continues to keep up a powerful army in profound peace, his neighbors must not suffer their vigilance to be entirely lulled to sleep by his bare word; and prudence requires that they should keep themselves on their guard. However certain they may be of the good faith of that prince, unforeseen differences may intervene; and shall they leave him the advantage of being provided, at that juncture, with a numerous and well disciplined army, while they themselves will have only new levies to oppose it? Unquestionably no. This would be leaving themselves almost wholly at his discretion. They are, therefore, under the necessity of following his example, and keeping, as he does, a numerous army on foot: and what a burden is this to a state! Formerly, and without going any further back than the last century, it was pretty generally made an article in every treaty of peace, that the belligerent powers should disarm on both sides — that they should disband their troops. If, in a time of profound peace, a prince was disposed to keep up any considerable number of forces, his neighbors took their measures accordingly, formed leagues against him, and obliged him to disarm. Why has not that salutary custom been preserved? The constant maintenance of numerous armies deprives the soil of its cultivators, checks the progress of population, and can only serve to destroy the liberties of the nation by whom they are maintained. Happy England! whose situation exempts it from any considerable charge in supporting the instruments of despotism. Happy Switzerland! if, continuing carefully to exercise her militia, she keeps herself in a condition to repel any foreign enemies, without feeding a host of idle soldiers, who might one day crush the liberties of the people, and even bid defiance to the lawful authority of the sovereign. Of this the Roman legions furnish a signal instance, This happy method of a free republic, — the custom of training up all her citizens to the art of war, — renders the state respectable abroad, and saves it from a very pernicious defect at home. It would have been everywhere imitated, had the public good been everywhere the only object in view.

Sufficient has now been said on the general principles for estimating the justice of a war. Those who are thoroughly acquainted with the principles, and have just ideas of the various rights of nations, will easily apply the rules to particular cases.


     1.    See further, as to what are, or are not, just causes for rescinding a treaty of peace, and which seem also to be here applicable, post. B. 4, ch. 4, § 41, 45, p. 49.
     2.    Livy, lib. v. cap. 49.
     3.    Aitial. Histor. lib. iii. cap. 6.
     4.    Prophaseis
     5.    Livy, lib. ix. init.
     6.    Of France.