When from peace or other causes the invest ment ceases, the blockade must be declared raised. See Snow, -Manual of International Law (2d ed., Washington, 1S9S).
The maintenance of an effective naval block ade depends primarily upon the possession of great naval superiority by the blockading force. From the standpoint of grand strategy, the blockade of an enemy's coast is desirable if the enemy depends upon foreign countries for his munitions of war, or the materials of which they are made; or if the sea affords assistance to his land operations; or for the protection of the commerce of the nation establishing the blockade. A blockade may be desirable for the purpose of cutting off food-supplies and general imports; but its importance, based on those grounds, is frequently overestimated. For it must be understood that those countries which import a large part of their food do so because they can purchase it cheaper than they can pro duce it—not because the production is beyond their capacity. A blockade which would interrupt foreign supplies would stimulate domestic pro duction and divert labor from the remunerative employments to that of agriculture. A country which depends upon the sea for its food likewise depends upon it as an outlet for its manufactures, and the financial disturbance caused by closing tile foreign market to its exports is quite as likely to cause suffering and bring the nation to seek terms of peace as the threatened scarcity of food which an interval of a few months is likely to cure. The importance of maintaining a blockade depends largely upon the amount of trade interrupted. If a country has a land frontier, it is manifest that this must be con trolled or the blockade will be annoying only and not vitally important. The seaport towns would suffer, but the country might continue to be but little affected.
The difficulty of maintaining a blockade is at present less than it has been at any time in the history of maritime war, notwithstanding the torpedo-boat — surface and submarine. The ac tual blockading force need be composed of light vessels only. in part of the large torpedo craft commonly called torpedo-boat destroyers. The heavier ships, especially at night, should lie farther out, beyond the easy range of torpedo boat attack, lint in supporting distance of the inner fleet should the enemy attempt a sortie in force. The maintenance of this condition de pends upon the position of a base in the enemy's territory where coal and supplies may be taken on board, or where at least there may be found a safe anchorage and refuge for the smaller ships in case of very heavy weather. During the con tinuance of such weather the heavy ships can move farther in, replacing the lighter ones which have been compelled to leave station, so that the blockade is not broken.
The most perfect blockade of a long coast was that maintained by the United States Navy during the Civil War. The conditions were as
favorable as ever can be expected. The South possessed a long land frontier, but except along the Mexican border it was dominated by the United States forces. The navy held several bases in the enemy's territory, and could have had others had it been deemed necessary. As the South had almost no seagoing naval force, many of the blockading ships were lightly armed mer chantmen commissioned as auxiliaries. Block ading fleets will always be largely composed of such craft if the extent of blockaded coast is great, because no nation has a sufficient number of regularly built war-ships available for such duty, and for stopping merchant vessels they are quite as good as more powerfully armed and better protected ships. If the enemy still pos sesses seagoing fighting ships, they must be kept in port by an adequate force of fighting ships. or they may escape and raise the blockade of ports where the enveloping fleet is weak. One of the closest blockades ever maintained was that of Santiago by the fleet under Admiral Sampson during the Spanish War. Seven of the heaviest ships in the navy lay in a semicircle about the entrance to the harbor, about two thousand yards apart, and from four to six thousand from the entrance. In addition to these were several cruisers, auxiliary yachts. and torpedo boats. At night, auxiliary cruisers and steam launches patrolled the entrance, which was light ed up by search-lights of one of the battle-ships. Not even a skiff could have left the harbor un observed.
The establishment of a blockade of the enemy's coast protects a country's commerce because it prevents, or tends to prevent, the fitting out of cruisers to prey upon it. But the war against commerce—what the French call the guerre de course—is becoming of less and less importance. The capture of merchant vessels has never affected the result of war. and the operations of 'commerce-destroyers' are likely to be attended with difficulties. It is no longer possible for them to keep the sea for long periods, as their radius of action is limited by their coal-supply. Furthermore, merchant vessels of belligerents are likely to be transferred to neutral flags if the insurance rates rise unduly through greatly in creased danger of capture. And, lastly, the ten dency of modern warfare is toward increased exemption of private property from capture.
A military blockade is designed to shut off an enemy from his source or base of supplies, make him ineffective, and eventually force him to sur render through lack of food, water, ammuni tion, or other supplies. It is not a regular siege, in the sense that organized efforts are made to take the base by assault; neither is it necessarily accompanied by a regular bombardment, though it may be subject to such intermittently. The military blockade, from the point of interna tional law, does foot occupy so important a place as the naval operation.