THE sea term blockade can claim as its progenitor an older military term, the word siege. Siege itself is a form of warfare limited both in conception and application. A general campaign which is being conducted along a broad front often passes beyond some strong and obstinately held position or place. An encircling force is left behind to capture the position in question, either by direct assault or, more probably, by preventing all succor in the shape of weapons or supplies from reaching the beleaguered occupants. Hence, unless the place has been evacuated of its civil population, the hardships of siege fall alike upon them and the fighting forces. Previous to the appearance of the concept of total war, the civil population were usually classed as non-combatants. However, siege was not considered an inhumane practice, even though it entailed general starvation. The besieged always had the choice whether to hold out or surrender.
In its first concept blockade was, like siege, a limited form of warfare. Only those ports were considered blockaded which had to seaward of them a sufficient naval force to prevent safe ingress and egress. A ship attempting to run the blockade was a legal capture irrespective of the character of the cargo carried. But even such a ship was not destroyed unless she first refused to stop. Beyond the limits of the immediate blockaded zone, international law prescribed certain definite rules of procedure covering search on the high seas, to determine the character of the cargo carried, its ultimate destination, and whether it consisted in whole or in part of contraband. The ship was never endangered and the lives of those on board were not jeopardized unless she resisted the legal right of search. A ship was not permitted to be destroyed on the high seas unless it was impossible to bring her into port for legal adjudication. In all cases where a ship was destroyed, every provision had to be taken to assure the safety of the personnel. Thus it can be seen that under the guidance of international law the practice of sea war was as humane in its attitude toward persons not actually engaged in combat as any form of war can be.
The first use of the system of total blockade did not originate with sea-minded Britain, nor was World War Number One the first time it was tried. After overrunning the Continent of Europe, and finding the invasion of Britain impossible, Napoleon declared the Continental blockade of the British Isles. This meant that no nations under his military influence could trade with England. He hoped thus to bring England to terms, reduce her influence on the Continent, and lessen the sea and financial power which had made her a great thorn in his side ever since the beginning of his career of expansion. Not being able to meet Britain on the seas, Napoleon had to exert military pressure on her as best he could. How like his action then is Hitler's pressure on Britain today! But because Tsar Alexander, who had at first concurred in Napoleon's plan, finally broke away, Napoleon turned on Russia. War with that country resulted in the débâcle before Moscow, which, with the campaign in Spain, was the beginning of the end.
During the last war Britain further extended the principle and practice of blockade, which, as already indicated, was originally designed to prevent contraband, i.e. supplies of military value, from reaching the enemy. The "Kirkwall practice," which required neutral ships to put into certain ports for examination, clearance or detention, represented an evolution in this practice. "Visit and search" became different from what it had previously been, and contraband as such ceased to exist. The net result was that blockade, previously intended to hamper the military life of an enemy nation, rapidly developed into an instrument for stopping the arteries of its economic life. In effect, the practice of siege was extended to entire nations, involving combatants and non-combatants alike. While this was going on, the United States remained neutral. By arming its ships it succeeded in evading the old right of visit and search on the high seas. For since the submarine is vulnerable to a single shot in its hull it could not carry on the customary procedure without risk of being sunk.
These practices by the Allies and by the United States led the Germans to establish their own counter-blockade methods -- unrestricted submarine warfare. The great distinction which has been drawn between the practices of the Allied and the Central Powers lay here. One gave the choice between life and death; the other did not. This is not the place to discuss the merits or demerits of this phase of the last war. The writer's only purpose is to show that one departure from established law leads to another.
In the last war submarines operated independently, and all were of the seagoing type. The small submarines of the present day were then unknown. The method of attack at first was to come to the surface, fire a gun, board the ship, put its crew in boats, place bombs in the hull, and in that way sink it. The advantage of sinking a ship by gunfire and bombs was that this did not waste a torpedo. Later on when all ships were armed the procedure became impossible, and then sinkings were effected by mines and torpedoes.
Convoys were not used until the spring of 1917. Ships continued sailing from various ports all over the world directly to the British Isles and to the Mediterranean. Even when submarine sinkings reached their height, in the spring of 1917, Admiral Jellicoe, First Sea Lord of the Admiralty, was loath to resort to the slow method of convoy, and finally yielded only after much persuasion from Admiral Sims. Before the introduction of convoys the chief protection given shipping was by the patrol system. Coming from ports all over the world, the ships bound for England entered what might be called a funnel-mouth on their way to London and Liverpool. The German submarines naturally operated around this congested spot. The British marked off the danger area into smaller areas, and a light craft, a destroyer if possible, was assigned to patrol each such area. Needless to say, this method of hunting submarines was not effective. The sinkings went on apace, until cut down by the shift to convoys. In distant seas, meanwhile, raiders took their toll of shipping also. But raiding never has been the menace to shipping that submarine warfare is, and never can be.
We adopted the convoy system as soon as we entered the war, though we never did arrive at the point where we could afford to give as efficient protection to cargoes as to troopships. However, our aid eased the strain and greatly helped the Allies protect cargo ships bound for their own ports. We did not try to convoy all our ships. Those capable of making 19 knots or more sailed alone. The convoys were never so large as they are in this war. One of thirty ships was considered very large. Our practice on this side of the ocean was to give Admiral Sims notice of the time and latitude when the convoy would pass longitude 30 degrees W. Command during the passage was vested in a commissioned officer, on board of an auxiliary cruiser or some naval craft. He led the way, gave all the orders, set its courses, and directed when and how the zigzag (the simultaneous change of course of ships in column) should be carried out. As ports on the Irish Coast as well as the French Channel ports were then open to the use of the Allies, the problem of protecting ships at sea was infinitely easier than it is today, especially since air attack must now be guarded against in addition to the danger from submarines.
Immediately upon the start of the present war the British readopted the convoy system. But the neutrality of the United States left Halifax, Nova Scotia, as practically the only large port on this side of the Atlantic from which Allied convoys could sail. As our aid in the way of supplies increased, a congestion of shipping in Halifax naturally resulted, and this meant that individual convoys became larger than they should be for efficient handling. The British also were forced to include in these big convoys vessels of low speed, which naturally handicapped the faster vessels.
The patrol system was still followed on distant seas, however, as a measure of protection against raiders. But up to the time the Graf Spee became active (she was eventually destroyed in the engagement off Montevideo) the raider problem presented no serious difficulties to Britain, at any rate none at all comparable to those in the last war. The British did not have the numbers of small naval craft available for escort duty that they had in the last war. Nevertheless until France fell they could count on the assistance of such French naval craft as were not engaged in convoy work in the Mediterranean. Again, the British Grand Fleet in this war did not have to stand watch and guard over a formidable German High Seas Fleet lurking in the Baltic, and this released many destroyers for escort duty.
The present war of the seas should be divided into two phases -- before the fall of France, and after. In the first phase, the Germans had to send their seacraft out from the Baltic or from North Sea ports. In fact, both the British and the Germans started the first phase of the sea war exactly where World War Number One left off. The Germans operated in the North Sea and close around the British Isles, using the individual submarine as the instrument of attack. Improvements had been made in the torpedo in the period between the two wars, but these were mostly in the direction of speed and accuracy of fire. No great change had been made in the weight of charge carried. Nor was this necessary, as it had been proved in the last war that one torpedo was usually enough to sink the ordinary cargo carrier. Both opponents had improved their listening devices, and in their newer and heavier naval craft the British had improved their underwater protection.
In the last war the Germans started their submarine offensive against naval vessels. But this time they at once made the merchant ship their main objective. Though they had a great air armada available, they looked on it more as a military than a naval asset. In fact, until they acquired the French bases its naval rôle was only as an adjunct to the submarine.[i] In this first phase of the sea warfare the Germans obtained the use of Norwegian bases, but their submarine campaign was not materially aided thereby. Their air power was still located too far away for it to be able to act efficiently in conjunction with the submarine.
The British reply to the Germans in this phase of the sea warfare was to block off the Straits of Dover, just as they had done in the last war. They also laid a mine field along the entire east coast of Scotland and England, with entrances and exits for Allied merchant shipping passing around Scotland or through the English Channel. As an additional precaution, they erected a balloon barrage to catch night flyers laying magnetic mines in the free seaway along the eastern coast. The west coast ports of Scotland and England remained fairly free for the use of shipping, since the main German submarine concentration was still in the North Sea. The close-in defense instituted by the British, conducted by their own air forces, by small craft such as trawlers and patrol boats, and by such destroyers as could be spared from escort duties, took so high a toll of submarines that the first phase of the sea war went decidedly against the Germans. The British were satisfied that they had the submarine fairly well under control.
But the second phase of the sea campaign has caused the British much greater concern. They have had to do without the naval assistance of France, while the Germans have gained that of Italy. Still more serious, control of French bases has enabled the Germans to conduct their submarine campaign from the Atlantic coast instead of the North Sea. Worse still, the Nazi air arm can now coöperate efficiently with the submarine. This is particularly important because the Nazis some time ago put the construction of small submarines on a mass basis, with an estimated production rate of around 25 a month. This figure may lead to miscalculations as to the number of submarines actually available. World War estimates of the actual number of submarines in operation proved later to have been too high. And in this war intensive RAF bombing of construction, repair and operating bases undoubtedly reduces the total of submarines which can be used efficiently. In general, only about one-third of the total number of submarines available can be at sea at one time. Crews are under a great strain and craft must be overhauled after any great length of time at sea. Nevertheless, it is a safe assumption that many more German submarines are at large in this war than in the last.
Furthermore, the plan of campaign has been changed. Instead of operating individually, the small submarines now work in groups, probably under the leadership of a larger submarine which is able to maintain radio contact with long-range scouting planes. This arrangement enables the submarines to spot each convoy and plan their attack with great accuracy. In fact, they no longer have to use their own periscopes to detect shipping, but can remain submerged until the time for attack arrives. No system of patrol can cope with submarine attack under such circumstances. The only answer is to increase the number of warships used on convoy duty.
Today the area of most intense danger for British shipping extends from 300 to 700 miles west of Ireland and from Iceland to the English Channel. When the convoys from America enter this zone they are subject to air bombing, which increases in intensity as they approach the British coasts. Possession of French Atlantic bases also enables Nazi submarines and air forces to prey efficiently upon convoys bound from Cape Town and the Mediterranean. In addition, long-range submarines operate well out in the Atlantic, as they did in the last war, to destroy such shipping as they may come upon there. The Nazis also decided, in this second phase of sea war, that the best use they could make of their heavier naval ships was to send them out as commerce raiders. The Hipper, Scharnhorst and Gneisenau have operated in the Atlantic, while other raiders, principally converted merchant ships, have worked in the Indian and Pacific Oceans.
The British have been hampered in dealing with these various onslaughts by the fact that they are constantly threatened with invasion, which has made it impossible for them to spare the small craft necessary to perform escort duty at sea properly. The number of such small craft on hand was inadequate in any case. Of these, a large proportion must be kept near home to prevent Nazi troops from crossing the Channel or coming in from Norway. The shortage of small ships used for convoy duty has enabled the German submarines to make attacks by night as well as by day. Indeed, some of the most successful German attacks have been made at night, by submarines operating on the surface.
The British have been further handicapped in convoy operations in the Atlantic by their campaign in the Mediterranean. Troop convoys must always be more heavily escorted than cargo ships, and there have been many troop movements in the Mediterranean, besides movements of supply ships. At all times, too, the main fleet must have its quota of destroyers, cruisers and aircraft. This still further diminishes the number of smaller naval ships available for escort duty. In consequence, a great burden has fallen on the smaller fishing boats and trawlers around the British Isles. They have performed their work nobly. But still the British have found no effective answer to the question of how to provide a greater measure of defense for their Atlantic shipping.
The fact is that what is required is teamwork between air and sea forces, and an increased number of each. The British have been handicapped by not being allowed the use of Irish bases. But even if they were, this would not compensate wholly for the insufficiency of their forces. Only America can supply what is needed now.
The first attitude of the United States towards the war was that we were neutral, but neutral in a limited sense. Thus we gave up freedom of the seas in favor of the cash-and-carry plan. We also joined the other American Republics in establishing a so-called neutrality zone, something hitherto entirely unknown in international law. This zone covered the waters about the coasts of the signatory American states, up to roughly a thousand miles, and included the whole Caribbean. A naval patrol was set up in this zone with the ostensible purpose of preventing any hostilities from taking place within it. The proclamation of the neutrality zone did not succeed in stopping hostilities, and its main purpose turned out to be to secure and make public information about any belligerent craft found operating there. This information was probably of more use to the British than to the Nazis. Since the British control the seas, they could use the information to direct the movements of their shipping and to pursue Nazi craft, whereas the only advantage to the Nazis was that the information might help them escape from danger. Our patrols were not empowered either in law or by executive order to drive enemy warcraft out of the neutrality zone.
Let us get some definitions straight. The term convoy is applied to a group of ships unable to defend themselves against attack and therefore in need of a protecting escort. The escort is responsible for its charge, the convoy, and must do its utmost to defend it. Hence the provision of an escort, though not an act of war, is an indication that the escorting ships intend to defend their charges even if this leads to fighting. But the escorting ships never fire the first shot unless they belong to a belligerent nation or are clearly within their rights in defending their own property within a sea area which their nation can claim as its own -- nominally, under the old rule of international law, the three-mile zone. The duties of patrols are various, depending on the instructions received. Their duties may merge into those of an escort; or they may lead them to range very widely over the seas. Patrols may be either non-belligerent or belligerent. When used by a non-belligerent the supposition is that they will not undertake any belligerent act. When used by a belligerent, however, it naturally is supposed that they will fight whenever they encounter an enemy.
Though the present total war has smashed many old precedents and rules it may have the effect of bringing new ones into force. The Americas took a first step in the declaration of a neutrality zone at sea. Our recent extension of the area under patrol to a thousand or more miles from our shores is a second step. Patrol within such a far-flung area can never have the same decisive results as escort. Yet it does have the effect of broadening the area in which the ships and planes of a non-belligerent, in the present case the United States, can receive and impart information of military importance. Even though such devices may not in the end prove to have affected decisively the course of the present war, they are interesting harbingers of a new order of international law more competent than the old to cope with the problems raised by modern total war.
[i] In conjunction with the submarine campaign, the Germans sprang a surprise with the magnetic mine. A counter for it was soon found, though actual contact with any form of mine always remained a danger.