[752] See, for instance, Hautefeuille, II. pp. 224 and 226; Calvo, V. § 2846; Fauchille, pp. 219-221.
As regards the practice of States, it has always been usual for the commander who established a blockade to send a notification of the blockade to the authorities of the blockaded ports or coast and the foreign consuls there. It has, further, always been usual for the blockading Government to notify the fact diplomatically to all neutral maritime States. And some States, as France and Italy, have always ordered their blockading men-of-war to board every approaching neutral vessel and notify her of the establishment of the blockade. But Great Britain, the United States of America, and Japan did not formerly consider notification to be essential for the institution of a blockade. They held the simple fact that the approach was blocked, and egress and ingress of neutral vessels actually prevented, to be sufficient to make the existence of a blockade known, and when no diplomatic notification had taken place, they did not seize a vessel for breach of blockade whose master had no actual notice of the existence of the blockade. English,[753] American,[754] and Japanese[755] practice, accordingly, made a distinction between a so-called de facto blockade on the one hand, and, on the other, a notified blockade.
[753] The Vrouw Judith (1799), 1 C. Rob. 150.
[754] See U.S. Naval War Code, articles 39-40.
[755] See Japanese Prize Law, article 30.
The Declaration of London, when ratified, will create a common practice, for articles 8 to 12 represent an agreement of the Powers on the following points:—
(1) There must be a declaration as well as a notification in order to make a blockade binding (article 8). If there is either no proper declaration or no proper notification, the blockade is not binding.
(2) A declaration of blockade is made either by the blockading Power or by the naval authorities acting in its name. The declaration of blockade must specify (a) the date when the blockade begins; (b) the geographical limits of the coastline under blockade; and (c) the period within which neutral vessels may come out (article 9). If the commencement of the blockade or its geographical limits are given inaccurately in the declaration, or if no mention is made of the period within which neutral vessels may come out, or if this period is given inaccurately, the declaration is void, and a new declaration is necessary in order to make the blockade binding (article 10).
(3) Notification of the declaration of blockade must at once be made. Two notifications are necessary (article 11):—
The first notification must be made by the Government of the blockading fleet to all neutral Governments either through the diplomatic channel, or otherwise, for instance by telegraph. The purpose of this notification is to enable neutral Governments to inform merchantmen sailing under their flag of the establishment of a blockade.