The second notification must be made to the local authorities by the officer commanding the blockading force; these authorities have on their part to notify, as soon as possible, the foreign consuls at the blockaded port or coastline. The purpose of this notification is to enable neutral merchantmen in the blockaded port or ports to receive knowledge of the establishment of the blockade and to prepare themselves to leave the port within the period specified in the declaration of blockade.
(4) The rules as to declaration and notification of blockade apply to cases where the limits of a blockade have been extended, or where a blockade is re-established after having been raised (article 12).
Length of Time for Egress of Neutral Vessels.
§ 377. As regards ingress, a blockade becomes valid the moment it is established; even vessels in ballast have no right of ingress. As regards egress, it has always been usual for the blockading commander to grant a certain length of time within which neutral vessels might leave the blockaded ports unhindered, but no rule existed respecting the length of such time, although fifteen days were frequently granted.[756] This usage of granting to neutral vessels a period within which they may leave the blockaded port, has been made a binding rule by the Declaration of London. For, since article 9 enacts that a declaration of blockade must specify the period within which neutral vessels may come out, it implicitly enacts that the granting of such a period is compulsory, although it may only be long enough to enable neutral vessels to make their way out as quickly as possible.
[756] According to U.S. Naval War Code, article 43, thirty days are allowed "unless otherwise specially ordered."
End of Blockade.
§ 378. Apart from the conclusion of peace, a blockade can come to an end in three different ways.
It may, firstly, be raised, or restricted in its limits, by the blockading Power for any reason it likes. In such a case it has always been usual to notify the end of blockade to all neutral maritime States, and article 13 of the Declaration of London turns this usage into a binding rule by enacting that the voluntary raising of a blockade, as also any restrictions in its limits, must, in the same way as the declaration of a blockade, be notified to all neutral Governments by the blockading Power, as well as to the local authorities by the officer commanding the blockading fleet.
A blockade can, secondly, come to an end through an enemy force driving off the blockading squadron or fleet. In such case the blockade ends ipso facto by the blockading squadron being driven away, whatever their intention as to returning may be. Should the squadron return and resume the blockade, it must be considered as new, and not simply the continuation of the former blockade, and another declaration and notification are necessary (article 12 of the Declaration of London).
The third ground for the ending of a blockade is its failure to be effective, a point which will be treated below in § [382].