[Sidenote: Manner of Pacific Blockade.] § 48. Pacific blockade is a measure of such enormous consequences that it can be justified only after the failure of preceding negotiations for the purpose of settling the questions in dispute. And further, as blockade, being a violation of the territorial supremacy of the blockaded State, is _prima facie_ of a hostile character, it is necessary for such State as intends in time of peace to blockade another State to notify its intention to the latter and to fix the day and hour for the establishment of the blockade. And, thirdly, although the Declaration of Paris of 1856 enacting that a blockade to be binding must be effective concerns blockades in time of war only, there can be no doubt that pacific blockades ought to be likewise effective. The declaration of the Institute of International Law in favour of pacific blockade contains, therefore, the condition: "Le blocus pacifique doit être déclaré et notifié officiellement, et maintenu par une force suffisante." [Sidenote: Value of Pacific Blockade.] § 49. As the establishment of a pacific blockade has in various instances not prevented the outbreak of hostilities, the value of a pacific blockade as a means of non-hostile settlement of international differences is doubted and considered uncertain by many writers. But others agree, and I think they are right, that the institution of pacific blockade is of great value, be it as an act of reprisal or of intervention. Every measure which is suitable and calculated to prevent the outbreak of war must be welcomed, and experience shows that pacific blockade is, although not universally successful, a measure of this kind. That it can give, and has in the past given, occasion for abuse in case of a difference between a strong and a weak Power is no argument against it, as the same is valid with regard to reprisals and intervention in general, and even to war. And although it is naturally a measure which will scarcely be made use of in case of a difference between two powerful naval States, it might nevertheless find application with success against a powerful naval State if exercised by the united navies of several Powers.[53] [Footnote 53: The following is the full text of the declaration of the Institute of International Law referred to above, § 45: "L'établissement d'un blocus en dehors de l'état de guerre ne doit être considéré comme permis par le droit de gens que sous les conditions suivantes: "1. Les navires de pavillon étranger peuvent entrer librement malgré le blocus. "2. Le blocus pacifique doit être déclaré et notifié officiellement et maintenu par une force suffisante. "3. Les navires de la puissance bloquée qui ne respectent pas un pareil blocus, peuvent être séquestrés. Le blocus ayant cessé, ils doivent être restitués avec leurs cargaisons à leurs propriétaires, mais sans dédommagement à aucun titre."] V INTERVENTION