§ 1. All causes of war can be referred either to defense, to reparation of loss, or to vengeance for injury inflicted upon God and men, both on behalf of one’s own state and on behalf of allies. Yet because among these there are various kinds and degrees of injuries, I shall speak of certain causes from which immense wars have arisen.
Injury to ambassadors has been the cause of serious wars, and a most just cause, because it is contrary to the law of nations. For if an ambassador is not safe, the hope of peace and reconciliation is cut off. The Tarentines foully violated the Roman embassy which carried a complaint concerning injured citizens, by an obscene insult shameful to relate. Florus, Book IV, chapter 8. But after being defeated in great battles, while Pyrrhus defended the impious cause in vain, they paid for the crime with slavery. The Picentes and Sallentines at the same time came under Roman dominion. Then the Illyrians cut down the ambassadors with an axe as though they were victims; but after victory, axes drawn over the necks of their princes made expiation to the hands of the ambassadors. Destruction was also brought upon Corinth because Roman ambassadors had been violated—whether by hand is uncertain, but certainly by speech.
King David waged a most serious and most destructive war, to the ruin of the nation, against the Ammonites. The cause was that Hanun had violated the ambassadors sent for friendship and consolation, 2 Samuel 10:4. “Therefore Hanun took David’s servants, shaved half of their beards, cut their garments in the middle as far as their buttocks, and sent them away.” What was more detestable, they hired Syrian auxiliaries against David and brought war upon him. For besides those who assisted the children of Ammon, who numbered 33,000, Hadadezer brought an immense multitude, of which David struck down 700 chariots and 40,000 horsemen. But after he had conquered Rabbah of the children of Ammon, he was very severe in victory, though by God’s command, 2 Samuel 12:31: “And bringing forth its people, he sawed them; and drove iron carts over them; and divided them with knives; and made them pass through the brick-mold. Thus he did to all the cities of the children of Ammon. And David and the whole army returned to Jerusalem.”
§ 2. There was no legitimate cause why Rome the daughter fought with Alba the mother; but each people, a kindred people, was afflicted until, weary of evils, they imposed the public decision upon the three Horatii and the three Curiatii. Five fell, and the sixth gave his innocent sister as a victim for himself. “Let the cause of the war be stated,” says Saint Augustine in The City of God, Book III, chapter 14, “as adultery was stated to be the cause of Troy: no such cause, nor anything similar, is found. It was only that Tullus might stir sluggish men to arms and troops now unaccustomed to triumphs.” Therefore, through that vice so great a crime of war between allies and kindred was perpetrated. It is surely shameful brigandage to make war merely for exercise.
§ 3. Some also are moved to arms by no other cause than the weakness and contemptibility of their enemies. They indeed have other causes for wishing it, but the enemies’ fortune causes them to dare it. This happens if a prince is weak in age or ability, if the people is rather alienated from him, or if a city has suffered fire or war. Thus, after Camillus had compelled the Gauls, when they had been cut down and put to flight, either to depart from Italy or to die, those who owed the Romans the greatest thanks attacked the wretched city with hostile minds—especially the Latins, when they demanded a share in the right of command and in the magistracies. This is one reason why the Empire deservedly remained unimpaired for the Romans, since they found their neighbors so ungrateful.
§ 4. Ambassadors are indeed inviolable and altogether immune, yet on this condition: that they do nothing beyond the office of their embassy, attempt nothing against those to whom they are sent, and, when ordered to depart, obey immediately. Accordingly, the ambassadors of the Tarquins deserved death when, under the opportunity of carrying away the royal furniture, they were purchasing traitors to the city. Livy, Book II: “Meanwhile, when the opinion which judged that the goods ought to be returned had prevailed in the senate, and when for that very cause the ambassadors had a reason for delay in the city—because they had obtained from the consuls time to procure wagons in which to carry away the kings’ possessions—they spent all that time consulting with the conspirators.”
The Romans could have punished them, but, lest they further provoke the Tarquins whom they feared, they dismissed them. The matter was of so great concern even to barbarians that when the Gauls attacked Clusium in war and confessed that they possessed no right except in arms, they nevertheless demanded that the Roman ambassadors be delivered to them because these had been seen in the front line and one had pierced the enemy’s commander. When they not only failed to obtain this but also learned that the violators of human law had been given the military tribunate, they immediately flew upon Rome. They valued the ambassadors’ deed more highly than their own. The Gauls were wresting land from its possessors by force and injury; the ambassadors, on behalf of innocent allies, were three men who had fought in the battle line, with no fault except that they had not been commanded to do so. Yet Rome paid for this fault with fire and near destruction. Therefore an ambassador must take care not to devise hostilities or have clandestine conversations, lest he appear to act as a spy and scout.
§ 5. The abduction of women and the avenging of violations of chastity have frequently been causes of foreign wars, just as they have been of seditions. The children of Israel, especially Simeon and Levi, avenged the violation of their sister Dinah by the destruction of the Shechemites. For one family made war upon an entire city, impiously and with broken faith; they had made peace and abused the sacrament of circumcision for deceit. The cause of the war was indeed just, but after the treaty the war became most unjust.
The Trojan War also arose from adultery, and the Messenian War, which divided Greece into parties, from fornication. The carrying off of Lavinia also roused Turnus to arms. And the first Roman arms, on account of the virgins abducted at the equestrian games, were employed between sons-in-law and fathers-in-law. The Veientines, Caeninenses, and Sabines justly brought war, but because they waged it with remarkable arrogance, they yielded to Roman arms.