1416. Stratagems in War.—(a) It is lawful to use various artifices for concealing one’s plans from the enemy, such as camouflage, smoke screens, censored reports of engagements, etc. Thus, Josue by command of the Lord prepared an ambush for the citizens of Hai (Jos., viii. 2). (b) It is lawful also to conceal one’s identity by wearing the uniforms of the enemy in order to obtain information about his plans. The Lord commanded Moses to send out men to spy on the land of Chanaan (Num., xiii. 1). While it is not lawful to tell or signify untruth, it is lawful to conceal the truth from those who have no right to know it.
1417. Reprisals are acts of retaliation by which one replies to unlawful aggressions of the enemy by equivalent aggressions against him. Their morality depends on circumstances. (a) Thus, if the act of the enemy is opposed only to international law, it is not unlawful to use the same act against him, for, since he has broken faith, the treaty obligation no longer binds the other side. For example, if the enemy, contrary to agreement, uses poison gas in warfare, it is lawful to use poison gas against him. Reprisals should not be made, however, without authorization from the proper authority. (b) If the act of the enemy is opposed to natural law, it is not permissible to retaliate by the same kind of acts. Two wrongs do not make a right. But one may retaliate in lawful ways, or else issue a protest and await compensation at the conclusion of the war. Thus, if the enemy murders the civil population, this does not justify one in murdering enemy citizens who are in one’s power.
1418. Duties of the Nation Victorious in War.—(a) The victorious nation must not prolong the war after victory has been gained, or after the enemy has sued in good faith for peace or armistice. (b) It must not exact from the defeated foe more than it has a just right to.
1419. The Rights of the Victor.—(a) If the cause of the victorious nation was unjust, its victory gives it no claim, for might does not make right. On the contrary, it may be obliged to make restitution to the defeated nation for the losses it has suffered. (b) If the cause of the victor was just, the victorious nation has a claim to three things: (i) to the satisfaction or restitution for the sake of which the war was undertaken; (ii) to compensation for damages caused by the enemy during the war, and (iii) to guarantees against a recurrence of the former injury. Supervision of peace treaties by an impartial tribunal has much to recommend it, since victors are prone to disregard charity and justice when treating with a conquered foe, and to extort from him forced agreements.
1420. The Obligation of a Victor Whose Cause was Unjust.—(a) If the victorious nation fought in good faith, and only later perceived the injustice of its cause, it is bound to restore only those things which it has not consumed, and which make it better off than it was before the war. (b) If it fought in bad faith, it should restore all. Victory does not prove that one was right, but only that one was stronger. It does not make a bad cause good.
1421. The Obligation of a Victor Who Fought Without Due Authorization, or with a Wrong Purpose.—(a) Soldiers who inflict damage on the enemy against the orders of the commanders (e.g., by burning dwellings, robbing private citizens, murdering, etc.), are obliged to restitution for those injuries, for such acts are not war, but brigandage. (b) Soldiers who fight with a wrong motive (e.g., out of hatred), are not obliged to restitution, since they have not committed injustice; for similarly a judge, who sentences a convicted criminal, sins if his motive is hate, but he is not held to restitution.
1422. What Indemnity may be Imposed on the Vanquished?—(a) According to justice, one may exact compensation for the losses and expenses one has sustained on account of war, since the enemy is responsible for these. (b) According to charity, one may be obliged to relinquish part of what is owed, or to grant easier terms of payment, or to cancel a debt, as when the enemy is greatly impoverished, or cannot easily pay at present.
1423. In cases of doubt, as when counter claims are made and neither party is entirely victorious, or when a vanquished nation denies its ability to pay what is demanded, recourse may be had to other ways of settlement. (a) Thus, in the former case a compromise or mutual condonation of claims, especially if both sides are exhausted by the war, seems the reasonable solution. (b) In the latter case submission to an impartial tribunal of arbitration would benefit the victors as well as the vanquished, since in the long run it is not to the advantage of the former that the latter be deprived of its goods and productivity.
1424. Guarantees for the Future.—(a) One may insist on such guarantees as will insure against a probable renewal of the offense committed by the conquered nation. Hence, one may require that it destroy or deliver over fortifications and munition plants, sink warships, reduce its military force, punish certain individuals, or depose certain rulers.
(b) One may not insist on such guarantees as will make a renewal of war by the enemy, now or in the future, absolutely impossible. As said above, a nation has the right to go to war to defend itself against aggression, but it has no right to work at destroying equality or competition on the part of other nations. Hence, it is not lawful to demand that the conquered nation surrender its independence or the management of its affairs, or that one be allowed to annex all the territory taken during war, if one’s rights or reasonable security does not require these conditions. Subjugation or temporary occupation are lawful, however, if there is no other way of obtaining redress or securities.