§ 1. “The life of man upon earth is warfare”; wherefore the Apostle commands me to labor like a good soldier of Christ Jesus. But does he enjoin that warfare by which the invader is deprived of life when he commands one to answer at the roll-call and to stand ready for battle? He proclaims spiritual warfare against the powers of the air, the rulers of these darknesses: “Let us therefore cast off the works of darkness and put on the armor of light” (Romans 13:12), which at 2 Corinthians 6:7 he calls “the armor of justice on the right hand and on the left.” For in truth, “though we walk according to the flesh, we do not wage war according to the flesh; for the weapons of our warfare are not carnal, but mighty through God for the destruction of fortifications” (2 Corinthians 10:4). What, then, has spiritual warfare to do with carnal weapons? What has it to do with those weapons by which an enemy is killed, if one must pray for enemies and do good to those who persecute us? Two objections, therefore, are made against one who treats of war. The first is that a man inexperienced in war cannot give precepts from the shade to those engaged in combat. The other is that this is least becoming to a priest and religious, whose office it is to protect books and temples:
Let men conduct war and peace, whose part it is to conduct war.
§ 2. At the threshold of this book I have set myself to answer these objections, so as to satisfy both the reproach of detractors and the question of the well-disposed.
And indeed, if it is objected that for a civilian to write about war is foreign to his condition and absurd—if they say, “Will you dare these things, you man of the study, who have never seriously seen a camp and have never, in short, touched any part of any military duty?”—Justus Lipsius, greater than envy and above slanders, already answered long ago on my behalf, in Book V of the Politics, chapter 1:
I indeed shall dare it, yet not through confidence in my own ability or powers, but in those from whom I have long borrowed and taken. For what is mine here? Some order and arrangement, perhaps. But those men go before me with their words and judgments, whom, I say confidently, any Hannibal, or Caesar himself, would not refuse to hear on this very matter. For what escaped those wise and illustrious men? Why should their judgment not be correct and pure here also? Some of them took part in wars, and indeed commanded them; others lived in that senate and among that people where these matters were the constant subject and activity. They therefore saw and heard and—what is chief—observed with judgment the very causes and origins of things, not only the προφάσεις [occasions] of events, but the αἴτια [causes] themselves. Alexander, truly Great in military affairs, did not hesitate to take and declare Homer his teacher in warfare: may I not therefore take these men with better right? For what did that poet sing of except one war, and that very war sprinkled with fables? He was certainly an extraordinary poet and more than a human poet, yet a poet nonetheless. Those men of mine—I plainly mean the historians—wrote of wars from almost every age, in a continuous series and with uncorrupted fidelity. Nor did they do only this; often, in the narration itself or outside it in speeches, as though intentionally, they mingled most salutary admonitions and counsels for every part of military affairs. What part or art of it do they not both set before us with examples and also touch upon in words: the army, camps, columns on the march, engagements, the assault of towns, provisions, the making and avoiding of ambushes, and the remaining matters proper to the administration of war? Since I have occupied myself in these matters for so many years, and with that inquisitive eye of the mind wander daily through those broad fields of the histories, why is it not lawful for me also to understand and judge something in them?
“You did not see them,” they say. Certainly; and therefore I claim for myself neither the practice nor the handling of weapons, but only an opinion and judgment, and even these bound to the opinion of another. Behold, in every gathering and even, if it please the gods, at banquets, there are men who command an army: they know where a camp must be placed, what places must be occupied by garrisons, when hands must be joined with the enemy, and when one must remain quiet. No one censures this. Am I a puppy and shameless if I say a word about these matters from the mind of the ancients? Iphicrates was once asked: τίς ὢν μεγαφρονεῖς; πότερον ἱππεὺς, ἢ τοξότης, ἢ πελταστής, ἢ ὁπλίτης; Οὐδεὶς ἔφη, τούτων, ἀλλ’ ὁ πᾶσι τούτοις ἐπιστάμενος ἐπιτάττειν. “Who are you, that you assume such lofty airs? Are you a cavalryman, an archer, a light-armed soldier, or a legionary?” “None of these,” he said, “but one who knows how to command all of them.” I shall emulate him in part and say: I am neither a commander nor a soldier, but one who may be able to give some counsel and advice to them at the proper time. I shall therefore proceed boldly and with no wavering step in my undertaking; and from the writings of the ancients, as though from gardens, I shall gather flowers of maxims and weave them into these garlands of chapters.
§ 3. Here, certainly, my case is the same, and so is my defense. For why should that be censured in insignificant me which is praised in that great man? And surely those who attribute everything to experience, but nothing to study, diligence, and ability, depart altogether too far from true wisdom and reason, since reason is the surest guide, whereas experience, although useful, is never so complete in every respect. Even if we listen to a long-lived and successful commander, that principle which soldiers themselves acknowledge nevertheless remains: sound reason is preferred to all examples. Yet I have determined to teach and confirm all my precepts by the examples of illustrious men, so that what is lacking in the author may be supplied by the completeness of the teaching. This ought to appear all the less novel because we read almost all books about war, as well as the histories, written by civilians, who also judge most prudently concerning commanders and the military counsels of kings although they themselves did not conduct wars.
Moreover, the choicest histories are explained to the young in academies for this purpose: not that they may understand the crimes of men and the slaughters stored in the annals, but that they may perceive what is to be followed and what avoided in every matter. No prudent person will judge it foreign to the historian’s office to discuss the manner of conducting war when he has learned at first glance that wars comprise the principal parts of history. Without this treatment, therefore, history can in no way be understood, nor can the more learned youth be properly instructed. Why, then, should anyone blame me if I set before the young the best precepts of peace and war from trustworthy history, when my calling, the inclination of my mind, and the love of my studies have long consecrated and bound me to the advantage of youth? If these precepts are bad, I now order them to be without effect; if they are good, even my enemies will have to praise them. I shall therefore give a history of war arranged in order, composed according to the rule of reason with the supports of examples, and confirmed and brought to completion not by my own ability but by the institutions of kings and great commanders.
§ 4. The second part of the objection is even more readily dissolved, although at first sight it appears absurd for a priest to treat of arms. To me, on the contrary, it seems that, for a good end and for just causes, priests sometimes can and ought to be disputants concerning war. Moses was a priest and an excellent warrior; Joshua, the minister of Moses, although he was not a priest, nevertheless joined piety with every distinction of war. Phinehas, the son of Eleazar the high priest, was appointed commander of the war against the Midianites by Moses. The Maccabean high priests conducted great wars; and why should I not be permitted to speak about war? Waging war is indeed forbidden to clerics by the canons; nevertheless, Saint Bernard advises Eugenius that wars are to be conducted not by his hand, but by his authority.
Clerics can sometimes take part in wars. For they can and ought to instruct the soldier in faith and piety, oppose the soldiers’ license, comfort the wounded, and administer the sacraments to the dying. No sound person doubts this matter.
They can also perform other duties: they may exhort the soldier to fight bravely, even carry the cross before him, and command him to be of great courage, as Maiolus says, Book V, chapter 49. God formerly willed that there be trumpets in the camps which the priests should sound and thereby procure victory for the warriors: “If you go forth to war from your land against the enemies who fight against you, you shall sound with howling trumpets, and there shall be a remembrance of you before the Lord our God, that you may be delivered from the hands of your enemies” (Numbers 10:9). For this reason Balaam also calls it the blast of the king’s victory which was in the tents of Israel. If a priest of the new law, placed amid the danger of war, kills an invader in necessary defense, he does not become irregular; in this case his condition is better than the soldier’s, for the soldier has voluntarily given his name in order to kill the enemy by public authority, whereas the cleric privately defends himself against an invader.
§ 5. Nor is war forbidden to clerics so severely that they cannot fight in a grave necessity or for some great advantage—if the fatherland is in danger, for example, or if the universal peace of the Church is hoped for. See Bañez, II–II, question 40, article 2; Henriquez, Book XIV, chapter 13. All also concede that clerics may fight by permission of the pontiff. A bishop certainly can declare war if this is necessary for recovering or defending his churches; accordingly, he will hold a levy, compel soldiers, and fortify himself with alliances and the assistance of princes. Thus Henriquez, Cajetan, Sylvester, and, before these, Saint Bernard and Pope Saint Leo.
Those judges, therefore, are exceedingly unjust toward us who, in order that they may easily wrench the chalice from us, attack us girded with swords and order us to be content with the breviary as our sole armor, as though it were not lawful for us to fight for our lawful possessions, altars, and temples, when there were two swords in the Lord’s household.
§ 6. Saint Thomas rightly teaches, II–II, question 32, article 2, that clerics are not permitted to fight because wars are very repugnant to clerical duties. They are deprived of the exercise of their orders, in Clerici and Quicumque, cause 13, question 8, and are ordered to be confined in a monastery. Yet because that law is not natural or divine, but ecclesiastical only, it not only can be removed by the legislator, but sometimes its obligation is removed by the very fact when another and graver law binds. For if the state is in grave danger and can be saved if clerics are enrolled among the soldiers, it is a right of nature that they too should fight with their own hands; for the obligation of natural law requires each man to defend his own state. And if in an offensive war the state is in the gravest necessity, a cleric will be able to fight in that war too with his own hand. Concerning defensive war, the opinion is unanimous that this is lawful in the utmost necessity or for the greatest advantage. Concerning offensive war they deny it; but it can happen that an offensive war is equally necessary, for in war it is often necessary to seize the initiative and forestall the enemy.
§ 7. Whatever reasons I set forth at the beginning for having undertaken the treatment of politics have their place here also. For the commander, legates, tribunes, and centurions must rely upon every kind of political prudence in order to govern an army—fierce men bearing arms—and this amid great dangers, from which disturbances and dissensions easily arise, since the men attribute favorable events to themselves and adverse events to their commanders. It therefore belongs to the highest art to govern the soldier; if this is rightly done, it is easy to conquer the enemy. Accordingly, I shall treat these matters with this end and in this manner: that by reading histories and accounts of wars the young may obtain benefit and, when their age has matured, may be able to conduct even necessary wars. Even the ill-disposed man ought to favor the attempt; I myself cannot guarantee its success.
We all owe very much to Lipsius, who, for the understanding of histories, kindled what he calls the Historical Torch, a name given not out of arrogance but by design: “That I may bring forward,” he says, “Roman customs, public and private—and elsewhere also Greek customs—and illuminate them in such a way that, at the same time, I may illuminate the passages of the ancient writers who allude to or touch upon them. Since this material is diffuse, and indeed confused—I cannot deny it—I resolved first to excerpt from the whole mass whatever bears upon warfare, to present it joined together and in some sequence and coherence of subjects. The reason for selecting what bears upon warfare is that it occurs in history not very frequently, but incessantly, and, so to speak, every page bears upon it. For as our life is public, so too is the writing of it: the former, from age to age, is disturbances and wars; therefore the annals that represent the age are so too. And I say knowingly and advisedly that nothing detains or delays the young more than ignorance of ancient warfare. Before all else we are going to remedy this evil and dispel this darkness with our torch, according to the measure of our ability.”
My purpose likewise is to exercise the young not only in understanding the deeds of the ancients, but also in reproducing them by imitation. For counsels are given concerning things that must be done. This pertains to the public good, which soldiers serve above all.
§ 8. Finally, since the studies of all political writers, jurists, theologians, scholastics, and canonists concerning war are extant, and since many questions pertaining to courts and conscience must be explained, it is manifest that I ought not to neglect this part, whether you regard theological or political treatises. To add to these some strategic counsels of great commanders will not be laborious for me, but will be most pleasing and fruitful for the young.
Yet my judgment is not that men accustomed to debate and declaim about wars should therefore be employed to conduct war; perhaps in battle they themselves, forgetful of all their precepts, would turn their backs to the enemy. Rather, let the state employ an experienced soldier who knows how to execute, not judge, the orders of commanders; but let it employ commanders who have also read these things and who can either use them or frustrate an enemy who uses them. For in battles, marches, and sieges various things happen contrary to expectation which demand immediate prudence. Then a commander trained both by reading and by waging war will be ready for sudden counsels. All these things tend to this: that counsel may be present in danger, and that commanders may extricate themselves in unexpected cases or entangle their enemies. For it belongs to a great commander to conquer by prudence, not by bloodshed. Indeed, to have deceived an enemy by a good stratagem is above every triumph.
I shall also add this: I was provoked by the example of an adversary. Machiavelli wrote about war, but did not dare to serve as a soldier, although the Duke of Urbino had urged him to do so. Cardano, On the Usefulness to Be Drawn from Adversity, Book III.