§ 1. It is not enough that wars be just and necessary unless the laws of war are also observed; for arms too have their laws, although they are opposed to laws. First, indeed, a war is sometimes rendered unjust and execrable from being just when it is waged by soldiers whom it was not proper to summon as auxiliaries. Then it can happen from this that neighboring princes and states can and ought, by right and desert, to assist those who previously supported an unjust cause, and to judge that cause to have been made just by the fault of the other party.
For if a Christian prince wages war with another who is likewise Christian, but brings in Turks, Tartars, or other unbelievers and barbarians as soldiers, there is no doubt that he sins most gravely, although he has a just cause for waging war. The reason is firm: although the other party has sinned and is bound to make satisfaction, it will nevertheless not be bound to deliver itself into the power of barbarians, which certainly occurs to the greatest detriment not only of bodies but also of souls. Nor can any prince or state exact from any prince or state the penalty that it open a gate to the Turk and commit its subjects to the utmost danger. Christian princes can also resist and rise against the man who has summoned unbelievers, contemners of treaties, and public enemies of all Christians. For in this manner they will not champion an unjust cause, but will avert a common danger which is accustomed to turn to the destruction not only of those against whom the barbarians are summoned and of the neighboring princes, but also of the very men who summoned them.
It has been customary in seditions to summon barbarians, and by this road the Heruli, Alans, Goths, Vandals, and Lombards invaded the empire. Palaeologus summoned Amurath against Marcus Craconicus, prince of Bulgaria, relying upon whom his nobles had rebelled. Rejoicing in the opportunity, Amurath first conquered on behalf of Palaeologus, and then subjected a great part of Greece to himself. Palaeologus waged a just war; but after he had employed a barbarous and perjured soldiery, he lost himself and his kingdom, and let into Europe a powerful enemy who now beats upon the barriers of Italy, Germany, and Spain. For this reason one must take care that high-spirited and lofty princes are not reduced by the injuries of their neighbors to attaching themselves to the common enemy. Thus, while Bayezid drove the conquered Christian Palaeologus to utter desperation, the latter was delivered after summoning Tamerlane; and Bayezid paid the penalties of fratricide—for he had killed his younger brother—and cruelty, being enclosed in a cage and led about as a mockery.
But let us return to the arms of barbarians. In 2 Chronicles 16 Asa is commanded to dismiss the army hired from Syria; and indeed, in chapter 19 Jehoshaphat is told: “Do you give aid to the impious and join in friendship with those who hate the Lord?” Nevertheless, arguments arise here which defend those auxiliaries. For no reason occurs why we may not employ every kind of soldier, whether faithful or unbelieving. For why, when we employ horses, elephants, and dogs against enemies, should it not be lawful to employ an unbelieving soldier, since they are ministers of justice, and in them piety is not required, but obedience? The Maccabees entered into an alliance with the Romans, and Jonathan assisted Demetrius. Indeed, in 1 Samuel 18 and 29 David joined himself to Achish, king of the Philistines. Finally, in most soldiers who are called Christians there is no great care for religion and piety. If, therefore, we seek the pious, the camps must be abandoned.
The answer is at hand. Nature has arranged it so that men seek every kind of aid for their own defense and do not attend to the piety or sins of the man assisting them. Therefore, considered in itself and by nature, it is not a crime to employ an immoral or unbelieving soldier; but because so many evils arise from it, the war is rendered altogether unlawful. Accordingly, a Christian prince unjustly driven from his dominion ought rather to live an innocent life in exile than to flee to the Turk in order to be restored by his forces. For in making war he will cast his subjects into servitude and cause slaughters—which indeed is lawful, for by the very fact that they revolted they deserved it. But it is contrary not only to charity but also to justice and the laws to subject them to unbelievers, so that they may be sold, compelled to Mohammedanism, and so that, by removing one dominion from the Christian world, he may make it weaker and increase the forces of the Turks by the addition; nor is the good he expects from it worth so much. For he will hold a precarious command beneath the proud scepter of the barbarian for so long as it pleases him. But if it were certain that the barbarous unbelievers would act humanely, use the victory according to the prince’s intention, not carry away the captured multitude, transport their army away, and claim no right for themselves, he could employ their labor. Yet this is the same as if you denied that barbarous unbelievers are barbarians. It has never yet happened; therefore it is not to be hoped that it will. Consequently, they are never prudently brought into the fatherland and are always lawfully repelled.
§ 2. In order that justice may be preserved in the war itself, it is lawful to inflict all those losses which pertain to punishing the guilty, making satisfaction, and establishing the safety of the state. When vengeance advances beyond those limits, the war is now unjust. The Lord God plainly abominates cruelty in battles. King Ahaz of Judah had offended the Lord and was delivered into the hands of the king of Israel, 2 Chronicles 28: “And Pekah son of Remaliah killed one hundred and twenty thousand men of Judah in one day, all of them men of war, because they had forsaken the Lord, the God of their fathers. And the children of Israel took from their brothers two hundred thousand women, boys, and girls, and immense spoil.”
But what did the prophet Oded say amid so great a rejoicing? “At that time,” says Scripture, “there was there a prophet of the Lord named Oded, who went out to meet the army coming to Samaria, and said to them: ‘Behold, the Lord, the God of your fathers, being angry against Judah, has delivered them into your hands, and you have killed them atrociously, so that your cruelty has reached to heaven. Moreover, you wish to subject the children of Judah and Jerusalem to yourselves as male and female servants, which ought by no means to be done. For in this you have sinned against the Lord your God. But hear my counsel, and lead back the captives whom you have brought from your brothers, because the great fury of the Lord hangs over you.’ Therefore men from among the princes of the children of Ephraim—Azariah son of Johanan, Berechiah son of Meshillemoth, Hezekiah son of Shallum, and Amasa son of Hadlai—stood against those who were coming from the battle and said to them: ‘You shall not bring the captives in here, lest we sin against the Lord. Why do you wish to add to our sins and heap up our former offenses? For the sin is great, and the anger of the Lord’s fury hangs over Israel.’ And the men of war left the spoil and everything they had captured before the princes and the whole multitude. And the men whom we mentioned above stood up and, taking the captives, clothed from the spoil all who were naked; and when they had clothed them, shod them, refreshed them with food and drink, anointed them because of their toil, and given them care, they placed upon beasts of burden all who could not walk and were weak in body, and brought them to Jericho, the city of palms, to their brothers; and they themselves returned to Samaria.”
Here the remedy exceeded its measure and vengeance the measure of the offense; therefore the immense fury of the Lord hung over them—not because it was unjust at the beginning, but because in a just war there was unjust atrocity. Thus, even when princes undertake just wars, they must beware the savagery of soldiers, lest a nation swift to monstrous deeds provoke God in the very victory.
§ 3. Compensation is not to be valued according to the enemies’ losses, but according to the victor’s advantage. For the enemies’ losses are accustomed to be immense. Whatever a soldier seizes in battle he retains by the law of war, and it does not pertain to satisfaction. It is an altogether equitable law that things captured in battle are considered to belong by right to those who capture them. For the freedom of commanders is necessary for encouraging the soldier. In Deuteronomy 20 all the spoil is said to be divided among the army. This is indeed taken from the enemy, but it is the wages of the soldiers; for in a just war the party which defends the unjust cause is compelled to restore the soldiers’ pay and whatever has been expended. It is lawful to kill armed men, to possess cities, and to do other things, because the enemies do and attempt all those things.
§ 4. A war in which innocent persons are killed is also waged unjustly, although it otherwise has a just cause. An innocent person, however, can be killed in two ways. First, one who is known to be innocent cannot be killed in himself and directly without sin. Exodus 23: “You shall not kill the guiltless and innocent”; and Deuteronomy 24: “Children shall not be killed for their parents.” The reason is taken from nature, because he who is free from fault ought not to sustain punishment. Injury is the cause of war; he who is removed from injury ought to be exempt from war. Moreover, the reasoning is the same for a subject city and a foreign one. For if Thessalonica sinned, Theodosius nevertheless could not involve the just and the seditious in the same punishment; nor does he have more power against foreigners, whose judge he has become for no other reason than their guilt. Hence in Deuteronomy 20 God pronounces that little children and innocent persons are to be spared. Children, women, and clerics are presumed innocent unless they have fought or assisted those fighting. Sometimes entire portions of armies can also be innocent: for all who believe that their prince is defending a just cause, although they bear arms, are to be considered innocent if only their ignorance is inculpable. Therefore they cannot be killed in themselves and directly as though lawfully condemned.
§ 5. Innocent persons are nevertheless killed incidentally, as the philosophers say. This occurs, first, because they are presumed guilty, as when, after a victory, all who are of military age are killed, because they are judged to have assisted by arms, counsels, or auxiliaries, and a soldier cannot hear and adjudicate the causes of individuals. Hence God spares only little children and women; without doubt, if men were known to be equally harmless, they would not be in a worse condition.
Second, although it were established that many are innocent, because war cannot be waged without their slaughter, they can be killed. For when a city is battered by artillery, the guilty and innocent are alike in the same danger. Third, when a city is given over to plunder, those who meet the soldiers are struck down everywhere without distinction; yet a commander can grant the spoil of the whole city, although he foresees that many innocent persons will perish. Indeed, if they place innocent persons upon the walls, he can pursue his right.
This occurred in the siege of Nicaea, where cruelty, heroic courage, and skill contended. Andronicus was besieging the city. When he saw the battering rams and machines being broken down, burned, and scattered, he entered upon the cruel counsel of placing upon the ram the mother of Isaac Angelus, who was then at Nicaea, and in this way setting the besiegers free to act. Nicetas narrates the history in his account of Andronicus:
“Therefore Andronicus, when he saw that his counsels lacked success, contrived an inhuman deed practiced by few before him. Euphrosyne, the mother of Isaac Angelus, summoned from Byzantium, he now placed before the machines as a bulwark, now struck the walls with her placed upon the ram. Thus at the same time the novelty of the spectacle, the monstrous anger recoiling from no crime, and the endurance of the poor woman—not deprived of life by fear itself amid so great and dangerous an assault—provoked pity and wonder. Then for the first time mortals saw a tender woman placed before iron for the sake of defense and, by a wonderfully inverted order, the frail body of a human being joined to the strongest machines so that those who fought from them might remain unharmed. Missiles were hurled from the walls just as before, but with so much care that, while the noble woman remained unharmed—as though she turned the missiles away from herself with nods and hands and drove them into the hearts of the enemies—they both struck and terrified the enemy.
“That monstrous deed profited Andronicus so little that the Nicaeans, making a sortie by night, both burned the machines and drew the woman by a rope into the city, leaving him to lament like Phineus despoiled by the Harpies, since he had nothing with which to satisfy the hunger of his anger. Thus the Nicaeans, having obtained praise for courage from the enemies themselves, conceived greater spirits and fought more boldly—not only by strenuously defending the walls and assailing Andronicus with taunts, calling him a butcher, a bloodthirsty dog, a rotten corpse, an immortal evil, a Fury of mankind, a womanizer, a Priapus older than Tithonus and Saturn, and, finally, abstaining from no name for a most shameful thing, but also by leaving the defenses and bursting forth from the gates.”
§ 6. Hence it comes about that sometimes each party wages a just war, when some part of a guilty state is innocent and defends itself justly as innocent, while the other attacks it as part of the guilty state. Hence there is something similar in a man who has been condemned in accordance with the allegations and proofs, but unjustly: he can both defend himself justly, and the judge condemns him justly, because he acts according to the laws; yet the condemnation is unjust because it is the condemnation of an innocent man.
§ 7. Innocent persons can nevertheless be despoiled, because the state has greater power over the property of an innocent person than over his life. For the common advantage, it can take away a private person’s property; it cannot take away his life. Nevertheless, the laws which have been enacted must be observed, as in the year 1570, article 69: “Let no one despoil a plough, a mill, an oven, or anything adapted for use, whether it belongs to friends or enemies; without license, let him destroy or break none of these things; let them not wantonly pour out or spoil wine, grain, or flour. Let death be the penalty for a transgressor.” By the same penalty it is forbidden for anyone to kill old men, priests, preachers, or unarmed women.
A penalty which consists in the loss of goods and liberty, however, can for weighty causes be inflicted upon innocent persons. This is accustomed to occur in all wars. For when God permits spoil to the soldiers, and when he commands a city to serve under tribute, that penalty is imposed upon all, even upon their posterity. Yet the cause of the loss inflicted is the prince who defends an unjust cause, and he is bound to restore their property to the innocent persons.