[23] This came about in two ways. The Church of Rome discouraged the growth of national sentiment. At the Reformation the independence and unity of the different nations were for the first time recognised. That is to say, the Reformation laid the foundation for a science of international law. But, from another point of view, it not only made such a code of rules possible, it made it necessary. The effect of the Reformation was not to diminish the number of wars in which religious belief could play a part. Moreover, it displaced the Pope from his former position as arbiter in Europe without setting up any judicial tribunal in his stead.
[24] Cf. Cicero: De Officiis, I. xi. “Belli quidem aequitas sanctissime feciali populi Romani jure perscripta est.” (See the reference to Lawrence’s comments on this subject, p. 9 above.)
“Wars,” says Cicero, “are to be undertaken for this end, that we may live in peace without being injured; but when we obtain the victory, we must preserve those enemies who behaved without cruelty or inhumanity during the war: for example, our forefathers received, even as members of their state, the Tuscans, the Æqui, the Volscians, the Sabines and the Hernici, but utterly destroyed Carthage and Numantia.... And, while we are bound to exercise consideration toward those whom we have conquered by force, so those should be received into our protection who throw themselves upon the honour of our general, and lay down their arms,” (op. cit., I. xi., Bohn’s Translation).... “In engaging in war we ought to make it appear that we have no other view but peace.” (op. cit., I. xxiii.)
In fulfilling a treaty we must not sacrifice the spirit to the letter (De Officiis, I. x). “There are also rights of war, and the faith of an oath is often to be kept with an enemy.” (op. cit., III. xxix.)
This is the first statement by a classical writer in which the idea of justice being due to an enemy appears. Cicero goes further. Particular states, he says, (De Legibus, I. i.) are only members of a whole governed by reason.
[25] The saying is attributed to Pompey:—“Shall I, when I am preparing for war, think of the laws?”
[26] This implied, however, the idea of a united Christendom as against the infidel, with which we may compare the idea of a united Hellas against Persia. In such things we have the germ not only of international law, but of the ideal of federation.
[27] See Maine’s Ancient Law, pp. 50-53: pp. 96-101. Grotius wrongly understood “Jus Gentium,” (“a collection of rules and principles, determined by observation to be common to the institutions which prevailed among the various Italian tribes”) to mean “Jus inter gentes.” The Roman expression for International Law was not “Jus Gentium,” but “Jus Feciale.”
“Having adopted from the Antonine jurisconsults,” says Maine, “the position that the Jus Gentium and the Jus Naturæ were identical, Grotius, with his immediate predecessors and his immediate successors, attributed to the Law of Nature an authority which would never perhaps have been claimed for it, if “Law of Nations” had not in that age been an ambiguous expression. They laid down unreservedly that Natural Law is the code of states, and thus put in operation a process which has continued almost down to our own day, the process of engrafting on the international system rules which are supposed to have been evolved from the unassisted contemplation of the conception of Nature. There is, too, one consequence of immense practical importance to mankind which, though not unknown during the early modern history of Europe, was never clearly or universally acknowledged till the doctrines of the Grotian school had prevailed. If the society of nations is governed by Natural Law, the atoms which compose it must be absolutely equal. Men under the sceptre of Nature are all equal, and accordingly commonwealths are equal if the international state be one of nature. The proposition that independent communities, however different in size and power, are all equal in the view of the Law of Nations, has largely contributed to the happiness of mankind, though it is constantly threatened by the political tendencies of each successive age. It is a doctrine which probably would never have obtained a secure footing at all if International Law had not been entirely derived from the majestic claims of Nature by the Publicists who wrote after the revival of letters.” (Op. cit., p. 100.)
[28] The name “International Law” was first given to the law of nations by Bentham. (Principles of Morals and Legislation, XIX. § xxv.)