Janeiro, in 1810, it was declared, "that the two powers have agreed on an alliance for defence, and reciprocal guarantee against every hostile attack, conformably to the treaties already subsisting between them, the stipulations of which shall remain in full force, and are renewed by the present treaty in their fullest and most extensive interpretation." This treaty confirms the stipulation of Great Britain to acknowledge no other sovereign of Portugal but the heir of the House of Braganza. The Treaty of Vienna, of the 22d January, 1815, between Great Britain and Portugal, contains the following article:-"The treaty of alliance at Rio Janeiro, of the 19th February, 1810, being founded on temporary circumstances, which have happily ceased to exist, the said treaty is hereby declared to be of no effect; without prejudice, however, to the ancient treaties of alliance, friendship, and guarantee, which have so long and so happily subsisted between the two crowns, and which are hereby renewed by the high contracting parties, and acknowledged to be of full force and effect."

Such was the nature of the compacts of alliance and guarantee subsisting between Great Britain and Portugal, at the time when the interference of Spain in the affairs of the latter kingdom compelled the British government to interfere, for the protection of the Portuguese nation against the hostile designs of the Spanish court. In addition to the grounds stated in the British Parliament, to justify this counteracting interference, it was urged, in a very able article on the affairs of Portugal, contemporaneously published in the Edinburgh Review, that although, in general, an alliance for defence and guarantee does not impose any obligation, nor, indeed, give any warrant to interfere in intestine divisions, the peculiar circumstances of the case did constitute the casus fœderis contemplated by the treaties in question. A defensive alliance is a contract between several States, by which they agree to aid each other in their defensive (or, in other words, in their just) wars against other States. Morally speaking, no other species of alliance is just, because no other species of war can be just. The simplest case of defensive war is, where our ally is openly invaded with military force, by a power to whom she has given no just cause of war. If France or Spain, for instance, had marched an army into Portugal to subvert its constitutional government, the duty of England would

have been too evident to render a statement of it necessary. But this was not the only case to which the treaties were applicable. If troops were assembled and preparations made, with the manifest purpose of aggression against an ally; if his subjects were instigated to revolt, and his soldiers to mutiny; if insurgents on his territory were supplied with money, with arms, and military stores; if, at the same time, his authority were treated as an usurpation, and all participation in the protection granted to other foreigners refused to the well-affected part of his subjects, while those who proclaimed their hostility to his person were received as the most favored strangers; in such a combination of circumstances, it could not be doubted that the case foreseen by defensive alliances would arise, and that he would be entitled to claim that succor, either general or specific, for which his alliances had stipulated. The wrong would be as complete, and the danger might be as great, as if his territory were invaded by a foreign force. The mode chosen by his enemy might even be more effectual, and more certainly destructive, than open war. Whether the attack made on him be open or secret, if it be equally unjust, and expose him to the same peril, he is equally authorized to call for aid. All contracts, under the law of nations, are interpreted as extending to every case manifestly and certainly parallel to those cases for which they provide by express words. In that law, which has no tribunal but the conscience of mankind, there is no distinction between the evasion and the violation of a contract. It requires aid against disguised as much as against avowed injustice; and it does not fall into so gross an absurdity as to make the obligation to succor less where the danger is greater. The only rule for the interpretation of defensive alliances seems to be, that every wrong which gives to one ally a just cause of war entitles him to succor from the other ally. The right to aid is a secondary right, incident to that of repelling injustice by force. Wherever he may morally employ his own strength for that purpose, he may, with reason, demand the auxiliary strength of his ally.1

1 Vattel's reasoning is still more conclusive in a case of guarantee: -“ Si l'alliance défensive porte une guarantie de toutes les terres que l'allié possède actuellement, le casus fœderis se déploie toutes les fois que ces terres sont envahies ou menacées d'invasion." Liv. iii. ch. 6, § 91.

Fraud neither gives nor takes away any right. Had France, in the year 1715, assembled squadrons in her harbors and troops on her coasts; had she prompted and distributed writings against the legitimate government of George I.; had she received with open arms battalions of deserters from his troops, and furnished the army of the Earl of Mar with pay and arms when he proclaimed the Pretender; Great Britain, after demand and refusal of reparation, would have had a perfect right to declare war against France, and, consequently, as complete a title to the succor which the States-General were bound to furnish, by their treaties of alliance and guarantee of the succession of the House of Hanover, as if the pretended king, James III., at the head of the French army, were marching on London. The war would be equally defensive on the part of England, and the obligation equally incumbent on Holland. It would show a more than ordinary defect of understanding, to confound a war defensive in its principles with a war defensive in its operations. Where attack is the best mode of providing for the defence of a State, the war is defensive in principle, though the operations are offensive. Where the war is unnecessary to safety, its offensive character is not altered; because the wrongdoer is reduced to defensive warfare. So a State, against which dangerous wrong is manifestly meditated, may prevent it by striking the first blow, without thereby waging a war in its principle offensive. Accordingly, it is not every attack made on a State that will entitle it to aid under a defensive alliance; for if that State had given just cause of war to the invader, the war would not be, on its part, defensive in principle.1

execution

§ 16. Hos- The execution of a treaty is sometimes secured by tages for the hostages given by one party to the other. The most of treaties. recent and remarkable example of this practice occurred at the peace of Aix-la-Chapelle, in 1748; where the restitution of Cape Breton, in North America, by Great Britain to France, was secured by several British peers sent as hostages to Paris.2

1 "Dans une alliance défensive le casus fœderis n'existe pas tout de suite dès que notre allié est attaqué. Il faut voir encore s'il n'a point donné à son ennemi un juste sujet de lui faire la guerre. S'il est dans le tort, il faut l'engager à donner une satisfaction raisonnable." Vattel, liv. iii. ch. 6, § 90.

2 Vattel, liv. ii. ch. 16, §§ 245-261.

Public treaties are to be interpreted like other laws 17. Inand contracts. Such is the inevitable imperfection and terpretation of treaties. ambiguity of all human language, that the mere words alone of any writing, literally expounded, will go a very little way towards explaining its meaning. Certain technical rules of interpretation have, therefore, been adopted by writers on ethics and public law, to explain the meaning of international compacts, in cases of doubt. These rules are fully expounded by Grotius and his commentators; and the reader is referred especially to the principles laid down by Vattel and Rutherforth, as containing the most complete view of this important subject.1

§ 18. Me

Negotiations are sometimes conducted under the mediation of a third power, spontaneously tendering its diation. good offices for this purpose, or upon the request of one or both of the litigating powers, or in virtue of a previous stipulation for that purpose. If the mediation is spontaneously offered, it may be refused by either party; but if it is the result of a previous agreement between the two parties, it cannot be refused without a breach of good faith. When accepted by both parties, it becomes the right and the duty of the mediating power to interpose its advice, with a view to the adjustment of their differences. It thus becomes a party to the negotiation, but has no authority to constrain either party to adopt its opinion. Nor is it obliged to guarantee the performance of the treaty concluded under its mediation, though, in point of fact, it frequently does so.2

The art of negotiation seems, from its very nature, § 19. Diplomatic hardly capable of being reduced to a systematic science. history. It depends essentially on personal character and qualities, united with a knowledge of the world and experience in business. These talents may be strengthened by the study of history, and especially the history of diplomatic negotiations; but the want of them can hardly be supplied by any knowledge derived

1 Grotius, de Jur. Bel. ac Pac. lib. ii. cap. 16. Vattel, liv. ii. ch. 17. Rutherforth's Inst. b. ii. ch. 7.

2 Klüber, Droit des Gens Moderne de l'Europe, Pt. II. tit. 2, § 1; ch. 2, § 160.

merely from books. One of the earliest works of this kind is that commonly called Le Parfait Ambassadeur, originally published in Spanish by Don Antonio de Vera, long time ambassador of Spain at Venice, who died in 1658. It was subsequently published by the author in Latin, and different translations appeared in Italian and French. Wicquefort's book, published in 1679, under the title of L'Ambassadeur et ses Fonctions, although its principal object is to treat of the rights of legation, contains much valuable information upon the art of negotiation. Callieres, one of the French plenipotentiaries at the Treaty of Ryswick, published, in 1716, a work entitled De la Manière de Negocier avec les Souverains, which obtained considerable reputation. The Abbé Mably also attempted to treat this subject systematically, in an essay entitled Principes des Negotiations, which is commonly prefixed as an introduction to his Droit Publique de l'Europe, in the various editions of the works of that author. A catalogue of the different histories which have appeared of particular negotiations would be almost interminable, but nearly all that is valuable in them will be found collected in the excellent work of M. Flassan, entitled L'Histoire de la Diplomatie Française. The late Count de Ségur's compilation from the papers of Favier, one of the principal secret agents employed in the double diplomacy of Louis XV., entitled Politique de tous les Cabinets de l'Europe pendant les Règnes de Louis XV. et de Louis XVI., with the notes of the able and experienced editor, is a work which also throws great light upon the history of French diplomacy. A history of treaties, from the earliest times to the Emperor Charlemagne, collected from the ancient Latin and Greek authors, and from other. monuments of antiquity, was published by Barbeyrac, in 1739.1 It had been preceded by the immense collection of Dumont, embracing all the public treaties of Europe, from the age of Charlemagne to the commencement of the eighteenth century.2 The best collections of the more modern European treaties are those published at different periods

Histoire des Anciens Traités, par Barbeyrac, forming the 5th vol. of Dumont's Supplement au Corps Diplomatique.

2 Corps Universel Diplomatique du Droit des Gens, &c., 8 tomes fol. Amsterd. 1726-1731. Supplement au Corps Universel Diplomatique, 5 tomes fol.