On the other hand, one speaks of guerilla war or petty war when, after the defeat and the capture of the main part of the enemy forces, the occupation of the enemy territory, and the downfall of the enemy Government, the routed remnants of the defeated army carry on the contention by mere guerilla tactics. Although hopeless of success in the end, such petty war can go on for a long time thus preventing the establishment of a state of peace in spite of the fact that regular war is over and the task of the army of occupation is no longer regular warfare. Now the question whether such guerilla war is real war in the strict sense of the term in International Law must, I think, be answered in the negative, for two reasons. First, there are no longer the forces of two States in the field, because the defeated belligerent State has ceased to exist through the military occupation of its territory, the downfall of its established Government, the capture of the main part and the routing of the remnant of its forces. And, secondly, there is no longer in progress a contention between armed forces. For although the guerilla bands are still fighting when attacked, or when attacking small bodies of enemy soldiers, they try to avoid a pitched battle, and content themselves with the constant harassing of the victorious army, the destroying of bridges and railways, cutting off communications and supplies, attacking convoys, and the like, always in the hope that some event or events may occur which will induce the victorious army to withdraw from the conquered territory. But if guerilla war is not real war, it is obvious that in strict law the victor need no longer treat the guerilla bands as a belligerent Power and the captured members of those bands as soldiers. It is, however, not advisable that the victor should cease such treatment as long as those bands are under responsible commanders and observe themselves the laws and usages of war. For I can see no advantage or reason why, although in strict law it could be done, those bands should be treated as criminals. Such treatment would only call for acts of revenge on their part, without in the least accelerating the pacification of the country. And it is, after all, to be taken into consideration that those bands act not out of criminal but patriotic motives. With patience and firmness the victor will succeed in pacifying these bands without recourse to methods of harshness.
II CAUSES, KINDS, AND ENDS OF WAR
Grotius, I. c. 3; II. c. 1; III. c. 3—Pufendorf, VIII. c. 6, § 9—Vattel, III. §§ 2, 5, 24-50, 183-187—Lorimer, II. pp. 29-48—Phillimore, III. §§ 33-48—Twiss, II. §§ 26-30—Halleck, I. pp. 488-519—Taylor, §§ 452-454—Wheaton, §§ 295-296—Bluntschli, §§ 515-521—Heffter, § 113—Lueder in Holtzendorff, IV. pp. 221-236—Klüber, §§ 41, 235, 237—G. F. Martens, §§ 265-266—Ullmann, § 166—Bonfils, Nos. 1002-1005—Despagnet, No. 506—Pradier-Fodéré, VI. Nos. 2661-2670—Rivier, II. p. 219—Nys, III. pp. 106-114—Calvo, IV. §§ 1866-1896—Fichte, Ueber den Begriff des wahrhaften Krieges (1815)—Rettich, Zur Theorie und Geschichte des Rechts zum Kriege (1888), pp. 141-292—Peyronnard, Des causes de la guerre (1901).
Rules of Warfare independent of Causes of War.
§ 61. Whatever may be the cause of a war that has broken out, and whether or no the cause be a so-called just cause, the same rules of International Law are valid as to what must not be done, may be done, and must be done by the belligerents themselves in making war against each other, and as between the belligerents and neutral States. This being the case, the question as to the causes of war is of minor importance for the Law of Nations, although not for international ethics. The matter need not be discussed at all in a treatise on International Law were it not for the fact that many writers maintain that there are rules of International Law in existence which determine and define just causes of war. It must, however, be emphasised that this is by no means the case. All such rules laid down by writers on International Law as recognise certain causes as just and others as unjust are rules of writers, but not rules of International Law based on international custom or international treaties.
Causes of War.
§ 62. The causes of war are innumerable. They are involved in the fact that the development of mankind is indissolubly connected with the national development of States. The millions of individuals who as a body are called mankind do not face one another individually and severally, but in groups as races, nations, and States. With the welfare of the races, nations, and States to which they belong the welfare of individuals is more or less identified. And it is the development of races, nations, and States that carries with it the causes of war. A constant increase of population must in the end force upon a State the necessity of acquiring more territory, and if such territory cannot be acquired by peaceable means, acquisition by conquest alone remains. At certain periods of history the principle of nationality and the desire for national unity gain such a power over the hearts and minds of the individuals belonging to the same race or nation, but living within the boundaries of several different States, that wars break out for the cause of national unity and independence. And jealous rivalry between two or more States, the awakening of national ambition, the craving for rich colonies, the desire of a land-locked State for a sea coast, the endeavour of a hitherto minor State to become a world-Power, the ambition of dynasties or of great politicians to extend and enlarge their influence beyond the boundaries of their own State, and innumerable other factors, have been at work ever since history was first recorded in creating causes of war, and these factors likewise play their part in our own times. Although one must hope that the time will come when war will entirely disappear, there is no possibility of seeing this hope realised in the near future. The first necessities of the disappearance of war are that the surface of the earth should be shared between States of the same standard of civilisation, and that the moral ideas of the governing classes in all the States of the world should undergo such an alteration and progressive development as would create the conviction that decisions of international courts of justice and awards of arbitrators are alone adequate means for the settlement of international disputes and international political aims. So long as these first necessities are not realised, war will as heretofore remain the ultima ratio of international politics.
Just Causes of War.
§ 63. However this may be, it often depends largely upon the standpoint from which they are viewed whether or no causes of war are to be called just causes. A war may be just or unjust from the standpoint of both belligerents, or just from the standpoint of one and utterly unjust from the standpoint of the other. The assertion that whereas all wars waged for political causes are unjust, all wars waged for international delinquencies are just, if there be no other way of getting reparation and satisfaction, is certainly incorrect because too sweeping. The evils of war are so great that, even when caused by an international delinquency,[76] war cannot be justified if the delinquency be comparatively unimportant and trifling. And, on the other hand, under certain circumstances and conditions many political causes of war may correctly be called just causes. Only such individuals as lack insight into history and human nature can, for instance, defend the opinion that a war is unjust which has been caused by the desire for national unity or by the desire to maintain the balance of power which under the present conditions and circumstances is the basis of all International Law. Necessity for a war implies its justification, whatever may be the cause. In the past many wars have undoubtedly been waged which were unjust from whatever standpoint they may be viewed. Yet the number of wars diminishes gradually every year, and the majority of the European wars since the downfall of Napoleon I. were wars that were, from the standpoint of at any rate one of the belligerents, necessary and therefore just wars.
[76] See above, [vol. I. §§ 151]-156.