There is only one point in connexion with this doctrine which requires attention. Is the action thus taken by the neutral Government a breach of its neutrality to the other belligerent? For, undoubtedly, it does act favourably to the belligerent who has declared the goods to be contraband. The answer is simple. Once admit the strict logic of the doctrine of ‘continuous voyages,’ it follows that an embargo is a measure neither directed against one belligerent nor imposed to favour the other. It is simply a measure of self-defence, taken in order to prevent the national industries from suffering from the undoubted belligerent right of detention at sea and possible seizure.
There are other occasions in which an embargo may be resorted to, as in the case of the embargo on rubber imported by Great Britain to which reference has been made above.[20] That is purely a municipal question with which international law can have no concern.
Blockade
And now I come to the last point of all, blockade, which is the supreme manifestation of force at sea for the purpose of crushing the enemy. Here all minor considerations vanish. The artificial distinction between absolute and conditional contraband disappears; there is no longer any free list; neutral as well as enemy cargoes are subject to seizure, whether going to or coming from the blockaded port. The humanitarian concession that war is not made on the civil population finds no place; indeed, blockade derives much of its efficacy from the pressure which the strangling process brings to bear on that population. It has been described as a siege carried on at sea, but under somewhat more elastic conditions than a land siege. It is a convenient comparison, because all the outcry against its inhumanity is silenced by the recollection of Paris in 1870, and the vision of what Paris would have been in 1914 if the German plan had succeeded. It is rigorous, almost brutal, but it is war, and war admits of no half-measures which come within the code of civilisation; and this measure, extreme though it be, has long been recognised as legitimate warfare. Nor is there any conventional limitation as to the time when it may be resorted to. Coming as it naturally does at the end of the discussion to which other principles have led up, it might appear as if custom had decreed that it should only be resorted to after all other measures had failed. But there is nothing to prevent a war starting with a blockade; nothing, that is to say, in the theory of the subject, though there are any number of practical reasons which make it improbable. I presume, however, that if a great maritime Power were at war with a State which had only a miniature fleet, a blockade of its coasts would be the speediest and, therefore, the most humane way of bringing it to a conclusion. Certainly there is no rule or custom which prevents a Power at war from putting forth its full strength at once.
The ascending scale is easier for purposes of study; the mind grasps smaller things more easily, and they prepare the way for the appreciation of the greater things. But it is not by a process of logical development that we reach blockade after a study of contraband. Blockade is treated last more conveniently because it involves the greatest development of force against the enemy; but it would have been more logical to have begun at the other end of the scale, starting with the greatest exhibition of force, and letting the series of rules emerge in diminishing strength. In view of what remains to be said, it is of great importance to appreciate that the incarnation of sea-power, blockade, which cuts the enemy off absolutely from the outer world, lies at one end of the scale of what one belligerent may do to the other, and the seizure of contraband on a neutral ship going to an enemy port, which cuts the enemy off but partially, lies at the other end. There can then be no difficulty in justifying what comes in between.
But the most curious point is that it is only when we come to the recognition of this extreme manifestation of force that we meet with artificial rules. A blockade must be ‘effective.’ Yet this word, as to the meaning of which in its ordinary use there can be no doubt, is given in treaties and by the authorities a wholly artificial meaning. Sometimes it includes the exact contrary to effectiveness, as that ‘A blockade is not regarded as raised if the blockading force is temporarily withdrawn on account of stress of weather’[21]: during which the adventurous skipper may run in. It is not necessary to labour the point; but it is necessary, when measures short of ‘blockade’ have been taken by England, that the full extent of what blockade pressure upon neutral trade means should be understood.
In order to determine what characterises a blockaded port, that denomination is given only where there is, by the disposition of the Power which attacks it with ships, stationary or sufficiently near, an evident danger in entering.[22]
A blockade [by cruising squadrons allotted to that service, and duly competent to its execution] is valid and legitimate, although there be no design to attack or reduce by force the port or arsenal to which it is applied, and that the fact of the blockade, with due notice given to neutral Powers, shall affect not only vessels actually intercepted in the attempt to enter the blockaded port, but those also which shall be elsewhere met with and shall be found to have been destined to such port, with knowledge of the fact and notice of the blockade.[23]
These two quotations embody the principles of the English prize law. Article 17 of the Declaration of London contains a modification of them, and provides that ‘neutral vessels may not be captured for breach of blockade except within the area of operations of the war-ships detailed to render the blockade effective.’