The Law of War and Peace (1625)

by Hugo Grotius

On Unjust Causes Of Wars

I.     The distinction between justifiable and persuasive causes is explained.
1.   We said above, when we set out to treat the causes of wars that some were justifiable, others persuasive. Polybius, who was the first to observe this distinction, calls the former ‘pretexts,’ because they are wont to be openly alleged (Livy sometimes employs the term ‘claim ‘), and the latter by the name of the class, ’causes.’

2.   Thus in the war of Alexander against Darius the ‘pretext’ was the avenging of the injuries which the Persians had inflicted upon the Greeks, while the ’cause’ was the desire for renown, empire, and riches, to which was added a great expectation of an easy victory arising from the expeditions of Xenophon and Agesilaus. The ‘pretext’ of the Second Punic War was the dispute over Saguntum, but the cause was the anger of the Carthaginians at the agreements which the Romans had extorted from them in times of adversity, and the encouragement which they derived from their successes in Spain, as was observed by Polybius. Likewise Thucydides thinks that the true cause of the Peloponnesian War was the power of Athens, which was on the increase and was regarded with suspicion by the Lacedaemonians, but that the pretext was the dispute over Corcyra, that over Potidaea, and other points of difference; in this, however, he confuses the terms ’cause’ and ‘pretext.”

The same distinction appears in the speech of the Campanians to the Romans, when they said that they fought against the Samnites nominally on behalf of the Sidicini, but in reality for themselves; because they saw that when the Sidicini had been consumed the conflagration would spread to them. Livy records also that Antiochus made war upon the Romans alleging as his reasons the execution of Barcillas and some other occurrences, but really because he had conceived great hopes of success from the decline in Roman discipline. In like manner Plutarch observes that Cicero incorrectly taunted Antony with being the cause of the civil war, since Caesar, having already decided upon war, merely found in Antony his pretext.’

II.     Wars which lack causes of either sort are wars of savages.
There are some who rush into war without a cause of either sort, led, as Tacitus says, by the desire of incurring danger for its own sake. But the offence of these men is more than human; Aristotle calls it ‘the savagery of wild beasts.’ Concerning such persons Seneca wrote: ‘I can say that this is not cruelty, but ferocity,’ which delights in savagery. We can call it madness; for there are various sorts of madness, and none is more unmistakable than that which turns to the slaughter and butchery of men.’

Altogether similar to this expression of opinion is that of Aristotle, in the last book of the Nicomachean Ethics: ‘For anyone would seem to be absolutely murderous if he should make enemies of his friends in order that there might be fighting and bloodshed.’ Said Dio of Prusa: ‘To wage war and to fight without a pretext, what else is this than utter madness and a craving for evils arising therefrom?’ The same idea is expressed by Seneca in his fourth Letter: ‘No one proceeds to shed human blood for its own sake, or at any rate only few do so.’

III.     Wars which have persuasive but not justifying causes are wars of robbers.
1.   In most cases those who go to war have persuasive causes, either with or without justifiable causes. There are some indeed who clearly ignore justifiable causes. To these we may apply the dictum uttered by the Roman jurists, that the man is a robber who, when asked the origin of his possession, adduces none other than the fact of possession.’

With regard to those who advocate war Aristotle says: ‘Do they oftentimes give no thought to the injustice of enslaving neighbors and those who have done no wrong? ‘

2.   Such a one was Brennus, who was wont to say that all things belonged to the stronger. Such, in the view of Silius Italicus, was Hannibal, for whom

      The sword
      The place of treaties and of justice took.

Such was Attila, and such were those whose lips are made to say:

      The issue of the war and not its cause
      We seek;


      Guilt will be his who in this battle fails;


      When fortune’s at its height, strength is the same as right.

To these you may fitly apply the saying of Augustine: ‘To make war upon our neighbors, and thence to advance against others, and from the mere lust of ruling to crush peoples who have not troubled us, what must we call this but wholesale robbery?’ Of wars of this type Velleius says: ‘They are wars entered upon for no good reasons, but for the gain they bring.’ In the first book of Cicero, On Duties, we read: ‘That exaltation of spirit seen in times of danger and toil, if it is devoid of justice, not only has in it no quality of virtue, but rather is a manifestation of a brutality that is hardened to all human feeling.’ Andronicus of Rhodes declared: ‘Those who, for the sake of great gains, take things whence they should not, are called wicked, impious and unjust. In this class are tyrants,’ and those who lay waste cities.’

IV.     There are certain causes which present a false appearance of justice.
Others allege causes which they claim to be justifiable, but which, when examined in the light of right reason, are found to be unjust. In such cases, as Livy says, it is clear that a decision based not on right but on violence is sought. Very many kings, says Plutarch, make use of the two terms, peace and war, as if they were coins, to obtain not what is right but what is advantageous.

Now causes which are unjust may, up to a certain point, be recognized from the foregoing discussion of just causes. What is straight is in fact a guide to what is crooked. For the sake of clearness, however, we proceed to mention the principal kinds of unjust causes.

V.     Such a cause is the fear of something uncertain.
1.   We have said above that fear with respect to a neighboring power is not a sufficient cause. For in order that a self-defense may be lawful it must be necessary; and it is not necessary unless we are certain, not only regarding the power of our neighbor, but also regarding his intention; the degree of certainty required is that which is accepted in morals.

2.   Wherefore we can in no wise approve the view of those who declare that it is a just cause of war when a neighbor who is restrained by no agreement builds a fortress on his own soil, or some other fortification which may some day cause us harm. Against the fears which arise from such actions we must resort to counter-fortifications on our own land and other similar remedies, but not to force of arms. The wars of the Romans against Philip of Macedon, and of Lysimachus against Demetrius, were, therefore, unjust, unless there was some other cause for them.

I am greatly pleased with what Tacitus says of the Chauci: ‘The noblest people of the Germans, who choose to defend their greatness by justice alone, without greed, without lawlessness. They are peaceful and retiring. They provoke no wars; they do not ravage with plunderings and brigandage. This is the outstanding evidence of their worth and power, that their position of superiority has not been attained by wrongful means. Yet all have arms in readiness, and, if the situation demands, they provide an army. They have great numbers of men and horses, and their reputation remains the same even though they are at peace.’

VI.     Another such cause is advantage apart from necessity.
Advantage does not confer the same right as necessity.

VII.     A cause of war presenting the appearance of justice is the refusal of marriage, when there is a great abundance of marriageable women.
So, when there is abundant opportunity for marriage, a refusal of marriage cannot furnish a cause for war; although in former times Hercules seized upon such a cause against Eurytus, and Darius’ against the Scythians.

VIII.     Such a cause, again, is the desire for richer land.
The desire to change abode, in order that by abandoning swamps and wildernesses a more fruitful soil may be acquired, does not afford a just cause for war. Tacitus says that this was a cause of warfare among the ancient Germans.

IX. Such a cause is also the discovery of things previously taken over by others.
Equally shameless is it to claim for oneself by right of discovery what is held by another, even though the occupant may be ‘wicked, may hold wrong views about God, or may be dull of wit. For discovery applies to those things which belong to no one.

X. What course is to be followed if the previous occupants are insane.
1.   For the exercise of ownership neither moral nor religious virtue, nor intellectual excellence, is a requirement; except that the view seems defensible that, if there exist any peoples wholly deprived of the use of reason, these cannot have ownership, but merely for charity’s sake there is due to them what is necessary to maintain life. What we have said elsewhere regarding the maintenance of ownership, which universal common law guarantees on behalf of minors and insane persons, applies to those peoples with whom there exists an interchange of agreements; but such are not peoples absolutely deprived of reason, if any of this sort are to be found, which I very much doubt.

2.   The Greeks were, therefore, wrong in saying that the barbarians were their enemies as it were by nature, because of their differences in customs, perhaps also because the barbarians seemed to be inferior to them in intellect. However, to what extent ownership may be taken away because of vicious crimes, which offend against both nature and human society, is another question, which we just now discussed when dealing with the right of punishments.

XI.     On unjust cause of war is the desire for freedom among a subject people.
Liberty, whether of individuals or of states, that is ‘autonomy,’ cannot give the right to war, just as if by nature and at all times liberty was adapted to all persons.’ For when liberty is said to be an attribute by nature of men and of peoples this must be understood of the law of nature which precedes all human conditions, and of liberty ‘by exemption,’ not of that which is ‘by opposition’; that is to say, that by nature no one is a slave, but not that man has the right never to enter slavery, for in that sense no one is free.

Here applies the saying of Albutius: ‘No one is born free, no one a slave; it is after birth that fortune has imposed these distinctions upon individuals.’ Also that of Aristotle: ‘By law, one man is a slave and another free.’ Wherefore those who from a lawful cause have come into personal or political slavery ought to be satisfied with their state, as Paul the Apostle teaches in the words: ‘Hast thou been called to be a slave? Be not concerned thereat.’

XII.     An unjust cause of war also is the desire to rule others against their will on the pretext that it is for their good.
Not less iniquitous is it to desire by arms to subdue other men, as if they deserved to be enslaved, and were such as the philosophers at times call slaves by nature. For even if something is advantageous for any one, the right is not forthwith conferred upon me to impose this upon him by force. For those who have the use of their reason ought to have the free choice of what is advantageous or not advantageous, unless another has acquired a certain right over them.

With infants the case is clearly different; for since they do not have the right of exercising ‘independence of action’ and of directing their own movements, nature confers the control over them upon persons who undertake it and are fitted therefor.

XIII.     An unjust cause of war is the title to universal empire which some give to the Emperor, and which is shown to be inapplicable.
1.   I should hardly trouble to add that the title which certain persons give to the Roman Emperor is absurd, as if he had the right of ruling over even the most distant and hitherto unknown peoples, were it not that Bartolus, long considered first among jurists, had dared to pronounce him a heretic who denies to the Emperor this title. His ground, forsooth, is that the Emperor at times calls himself lord of the world, and that in the sacred writings that empire, which later writers call Romania,’ is designated as ‘the inhabited world.” Of like character is this expression:

      Now the whole earth the victorious Roman held,

as are many similar expressions used in a broad sense, or in hyperbole, or in high praise; as when, in the same Holy Writ, Judaea alone often appears under the designation of’ the inhabited world.’ It is in this sense that we are to take the ancient saying of the Jews that the city of Jerusalem is situate in the center of the earth, that is in the center of Judaea,’ just as Delphi, in the middle of Greece, is likewise called the navel of the world.

Nor should any one be influenced by the arguments of Dante, by which he strives to prove that such a right belongs to the Emperor because that is advantageous for the human race. The advantages which it brings are in fact offset by its disadvantages. For as a ship may attain to such a size that it cannot be steered, so also the number of inhabitants and the distance between places may be so great as not to tolerate a single government.

2.   Again, even if we should grant that the ascription of such a right to the Emperor is advantageous, the right to rule by no means follows, since this cannot come into existence except by consent or by punishment. The Roman Emperor at present does not have this right even over all the former possessions of the Roman people; for as many of these were acquired by war, so by war they have been lost; while others by treaties, others still by abandonment, have passed under the authority of other nations or kings.’ Some states, too, that were once completely subject, later began to be subject only in part, or merely federated on unequal terms. For all these ways either of losing or of modifying a right are not less valid against the Roman Emperor than against others.

XIV.     An unjust cause of war is the title to universal empire which others give to the Church, and which also is shown to be inapplicable.
1.   There have also been some who claimed for the Church a right over the peoples even of the hitherto unknown parts of the earth, although the Apostle Paul himself clearly stated that he did not have the right to judge those who are outside the bounds of Christendom, saying: ‘For what have I to do with judging them that are without?’ (1Corinthians 5:12).

Yet the right of judging possessed by the Apostles, even although it extended in its own way to earthly things, was of a heavenly nature, so to say, and not of earthly quality; it was to be exercised indeed not by the sword and scourge but by the word of God enunciated in general terms and applied to particular conditions, through the revelation or denial of the signs of divine grace, according as each might deserve; in last resort even by a punishment not according to nature but from a higher source than nature, therefore emanating from God. A punishment of this kind appeared in the cases of Ananias, Elymas, Hymenaeus, and others.

2.   Christ Himself, the source of all ecclesiastical power, whose life is set as an example to the Church, in so far as it is His Church, declared that His kingdom was not of this world, that is, of the same character as other kingdoms; adding that otherwise He might make use of soldiers in the manner of other kings. As it was, if He had wished to call for legions, He would have called for legions not of men but of Angels (Matthew 26:53). Whatever He did by right of authority vested in Himself, He did not by human but by divine power, even when He cast the money-changers out of the Temple. For on that occasion also the scourge was a sign, not an instrument, of divine anger; as at other times the spittle and oil were a symbol of healing,’ not a remedy.

Augustine thus comments on the passage of John referred to:

Hear then, ye Jews and Gentiles; hear, O circumcision; hear, O uncircumcision; hear, all ye kingdoms of the earth! I do not interfere with your rule in this world ‘ My kingdom is not of this world.’ Fear ye not with the utterly empty fear with which the elder Herod trembled when the birth of Christ was announced, and slew so many children in order that death might reach that child; for he was rendered more cruel by his fear than by his anger.

‘My kingdom,’ He said, ‘is not of this world.’ What more do ye seek? Come to the kingdom that is not of this world; come believing, and rage not through fear.

3.   Among other things Paul forbids the bishop to use force (2Timothy 3:2). Chrysostom said that ‘to rule by compulsion,’ the compulsion, of course, which is derived from human power, ‘is the right of kings, not of bishops.’ Elsewhere he declares: ‘Power has not been given to us to restrain men from crimes by the authority of our sentences,’ sentences, that is, which involve the right of execution by royal or military power, or the deprivation of any human right whatsoever.’ He says also that the bishop should perform his office ‘not by compulsion but by persuasion.’ From this it is abundantly clear that bishops, as such, have no right to rule over men in the manner of this world. In comparing the king and the bishop, Jerome declares that ‘the former is set over unwilling, the latter over willing subjects.’

4.   The question whether even kings may use armed force as a means of punishment against those who reject the Christian religion we have previously discussed, so far as is necessary for our purpose, in the chapter ‘On Punishments.’

XV.     An unjust cause of war is also the desire to fulfil prophecies, without the command of God.
Not without reason shall I give this warning, that the hope derived from an interpretation of divine prophecies does not furnish a just cause of war. For from a comparison of modern with ancient events I foresee the danger of great evil from this source, unless we guard against it. Apart from the fact that without prophetic inspiration it is hardly possible to interpret with certainty prophecies that have not yet been fulfilled, even the times set for the coming of things that are certain may be hidden from us. Finally a prediction, unless it is a definite command of God, confers no right, since the things which God foretells He often permits to be accomplished through the agency of wicked men or base deeds.

XVI.     An unjust cause of war is also the desire to obtain something that is owed by an obligation not strictly legal but arising from some other source.
This principle, too, must be recognized. If a person owes a debt that is not an obligation from the point of view of strict justice, but arises from some other virtue, such as generosity, gratitude, pity or charity, this debt cannot be collected by armed force any more than in a court of law. For either procedure it is not enough that the demand which is made ought to be met for a moral reason, but in addition we must possess some right to enforce it.

This right is at times conferred by divine and human laws even in the case of obligations that arise from other virtues; and when this happens there arises a new cause of indebtedness, which relates to justice. When this is lacking, a war undertaken on such grounds is unjust, such as the Roman war against the King of Cyprus on the charge of ingratitude. He who confers a kindness has no right to demand gratitude; otherwise there would be an agreement, not an act of kindness.

XVII.     The difference between a war the cause of which is unjust and a war in which there is a wrong of another kind; and the different effects of each.
1.   It is to be observed that this often happens, that a just cause for a war may in fact exist, but that in making war a wrong may arise from the intent of the party who engages in hostilities. This may come about either because some other thing, not in itself unlawful, in a greater degree and more effectively influences his purpose than the right itself, as, for example, an eager desire for honor,’ or some advantage, whether private or public, which is expected from the war considered apart from its justifiable cause. Or there may be present a manifestly unlawful desire, such as the delight of him who has pleasure in another’s ill, without regard to what is good. From this point of view Aristides in his oration On the Alliance says that the Phocians perished in accordance with their deserts, but that Philip did not act rightly when he overthrew them, seeing that he did not act out of zeal for religion, as he pretended, but in order to extend his empire.

2.   ‘The sole cause of warfare, and that an ancient one,’ says Sallust, ‘is a deeply rooted desire for power and riches.’ ‘Gold and wealth, the chief causes of wars,’ we find in Tacitus. In a tragedy we read:

      Impious lust of gain and wrath impetuous
      Have broken the alliance.

With these quotations you may rightly associate the passage of Augustine: ‘The eager desire to injure, the cruelty of vengeance, the unappeased and unappeasable mind, the savagery of rebellion, the lust of ruling, and whatever else there is akin, these are the things which are justly censured in warfare.’

3.   However, when a justifiable cause is not wanting, while these things do indeed convict of wrong the party that makes war, yet they do not render the war itself, properly speaking, unlawful. Hence no restitution is due as a result of a war undertaken under such conditions.