Thirdly, there is the relation between the destructive power of modern cruisers and flotillas against a convoy unescorted or weakly escorted and the corresponding power in sailing days.

Fourthly, there is the relation between the speed of convoys and the speed of battle-squadrons, which is of importance where the enemy's transports are likely to be strongly escorted. On this relation depends the facility with which the battle-squadron covering our mobile defence can secure an interior position from which it may strike either the enemy's battle-squadron if it moves or his convoy before it can complete its pa.s.sage and effect the landing.

All these relations appear to have been modified by modern developments in favour of the defence. In the first ratio, that of speed of mobilisation to speed of intelligence, it is obviously so. Although military mobilisation may be still relatively as rapid as the mobilisation of fleets, yet intelligence has outstripped both. This is true both for gaining and for conveying intelligence. Preparations for oversea invasion were never easy to conceal, owing to the disturbance of the flow of shipping that they caused. Elaborate precautions were taken to prevent commercial leakage of intelligence, but they never entirely succeeded. Yet formerly, in the condition of comparative crudeness with which international trade was then organised, concealment was relatively easy, at least for a time. But the ever-growing sensitiveness of world-wide commerce, when market movements are reported from hour to hour instead of from week to week, has greatly increased the difficulty. And apart from the rapidity with which information may be gathered through this alert and intimate sympathy between Exchanges, there is the still more important fact that with wireless the speed of conveying naval intelligence has increased in a far higher ratio than the speed of sea transit.

As regards the ratio between cruiser and convoy speeds, on which evasion so much depends, it is the same. In frigate days the ratio appears to have been not more than seven to five. Now in the case at any rate of large convoys it would be nearly double.

Of the destructive power of the flotilla, growing as it does from year to year, enough has been said already. With the advent of the torpedo and submarine it has probably increased tenfold. In a lesser degree the same is true of cruisers. In former days the physical power of a cruiser to injure a dispersing convoy was comparatively low, owing to her relatively low excess of speed and the restricted range and destructive power of her guns.

With higher speed and higher energy and range in gun power the ability of cruisers to cut up a convoy renders its practical annihilation almost certain if once it be caught, and consequently affords a moral deterrent against trusting to evasion beyond anything that was known before.

The increased ratio of battle-fleet speed to that of large convoys is equally indisputable and no less important, for the facility of finding interior positions which it implies goes to the root of the old system. So long as our battle-fleet is in a position whence it can cover our flotilla blockade or strike the enemy's convoy in transit, it forces his battle-fleet in the last resort to close up on the convoy, and that, as Kempenfelt pointed out, is practically fatal to the success of invasion.

From whatever point of view, then, we regard the future chances of successful invasion over an uncommanded sea, it would seem that not only does the old system hold good, but that all modern developments which touch the question bid fair to intensify the results which our sea service at least used so confidently to expect, and which it never failed to secure.

II. ATTACK AND DEFENCE OF TRADE

The base idea of the attack and defence of trade may be summed up in the old adage, "Where the carcase is, there will the eagles be gathered together." The most fertile areas always attracted the strongest attack, and therefore required the strongest defence; and between the fertile and the infertile areas it was possible to draw a line which for strategical purposes was definite and constant. The fertile areas were the terminals of departure and destination where trade tends to be crowded, and in a secondary degree the focal points where, owing to the conformation of the land, trade tends to converge. The infertile areas were the great routes which pa.s.sed through the focal points and connected the terminal areas.

Consequently attack on commerce tends to take one of two forms. It may be terminal or it may be pelagic, terminal attack being the more profitable, but demanding the greater force and risk, and pelagic attack being the more uncertain, but involving less force and risk.

These considerations lead us directly to the paradox which underlies the unbroken failure of our enemies to exercise decisive pressure upon us by operations against our trade. It is that where attack is most to be feared, there defence is easiest. A plan of war which has the destruction of trade for its primary object implies in the party using it an inferiority at sea.

Had he superiority, his object would be to convert that superiority to a working command by battle or blockade. Except, therefore, in the rare cases where the opposed forces are equal, we must a.s.sume that the belligerent who makes commerce destruction his primary object will have to deal with a superior fleet. Now, it is true that the difficulty of defending trade lies mainly in the extent of sea it covers. But, on the other hand, the areas in which it tends to congregate, and in which alone it is seriously vulnerable, are few and narrow, and can be easily occupied if we are in superior force. Beyond those areas effective occupation is impossible, but so also is effective attack. Hence the controlling fact of war on commerce, that facility of attack means facility of defence.

Beside this fundamental principle we must place another that is scarcely less important. Owing to the general common nature of sea communications, attack and defence of trade are so intimately connected that the one operation is almost indistinguishable from the other. Both ideas are satisfied by occupying the common communications. The strongest form of attack is the occupation of the enemy's terminals, and the establishment of a commercial blockade of the ports they contain. But as this operation usually requires the blockade of an adjacent naval port, it also const.i.tutes, as a rule, a defensive disposition for our own trade, even when the enemy's terminal area does not overlap one of our own. In the occupation of focal areas the two ideas are even more inseparable, since most, if not all, such areas are on lines of communication that are common.

It will suffice, therefore, to deal with the general aspect of the subject from the point of view of defence.

It was in conformity with the distinction between fertile and infertile areas that our old system of trade defence was developed. Broadly speaking, that system was to hold the terminals in strength, and in important cases the focal points as well. By means of a battle-squadron with a full complement of cruisers they were const.i.tuted defended areas, or "tracts" as the old term was, and the trade was regarded as safe when it entered them.

The intervening trade-routes were left as a rule undefended. Thus our home terminals were held by two battle-squadrons, the Western Squadron at the mouth of the Channel, and the North Sea or Eastern Squadron with its headquarters usually in the Downs. To these was added a cruiser squadron on the Irish station based at Cork, which was sometimes subordinate to the Western Squadron and sometimes an independent organisation. The area of the Western Squadron in the French wars extended, as we have seen, over the whole Bay of Biscay, with the double function, so far as commerce was concerned, of preventing the issue of raiding squadrons from the enemy's ports, and acting offensively against his Atlantic trade. That of the North Sea squadron extended to the mouth of the Baltic and the north-about pa.s.sage. Its main function during the great naval coalitions against us was to check the operations of Dutch squadrons or to prevent the intrusion of French ones north-about against our Baltic trade. Like the Western Squadron, it threw out divisions usually located at Yarmouth and Leith for the protection of our coastwise trade from privateers and sporadic cruisers acting from ports within the defended area. Similarly, between the Downs and the Western Squadron was usually one or more smaller squadrons, mainly cruisers, and generally located about Havre and the Channel Islands, which served the same purpose for the Norman and North Breton ports. To complete the system there were flotilla patrols acting under the port admirals and doing their best to police the routes of the coastwise and local traffic, which then had an importance long since lost. The home system of course differed at different times, but it was always on these general lines. The naval defence was supplemented by defended ports of refuge, the princ.i.p.al ones being on the coast of Ireland to shelter the ocean trade, but others in great numbers were provided within the defended areas against the operations of privateers, and the ruins of batteries all round the British sh.o.r.es testify how complete was the organisation.

A similar system prevailed in the colonial areas, but there the naval defence consisted normally of cruiser squadrons stiffened with one or two ships-of-the-line mainly for the purpose of carrying the flag. They were only occupied by battle-squadrons when the enemy threatened operations with a similar force. The minor or interior defence against local privateers was to a large extent local; that is, the great part of the flotilla was furnished by sloops built or hired on the spot, as being best adapted for the service.

Focal points were not then so numerous as they have become since the development of the Far Eastern trade. The most important of them, the Straits of Gibraltar, was treated as a defended area. From the point of view of commerce-protection it was held by the Mediterranean squadron. By keeping watch on Toulon that squadron covered not only the Straits, but also the focal points within the sea. It too had its extended divisions, sometimes as many as four, one about the approaches to Leghorn, one in the Adriatic, a third at Malta, and the fourth at Gibraltar. In cases of war with Spain the latter was very strong, so as to secure the focal area against Cartagena and Cadiz. On one occasion indeed, in 1804-5, as we have seen, it was const.i.tuted for a short time an independent area with a special squadron. But in any case the Gibraltar area had its own internal flotilla guard under the direction of the port admiral as a defence against local privateers and pirates.

The general theory of these defended terminal and focal areas, it will be seen, was to hold in force those waters which converging trade made most fertile, and which therefore furnished an adequate field for the operations of raiding squadrons. In spite of the elaborate defensive system, such squadrons might, and sometimes did, intrude by surprise or stealth, and were then able to set at defiance both convoy escorts and the cruiser outposts. But, as experience proved, the system of terminal defence by battle-squadrons made it impossible for such raiding squadrons to remain long enough on the ground to cause any serious interruption or to do serious harm. It was only by a regular fleet of superior strength that the system could be broken down. In other words, the defence could only fall when our means of local control was destroyed by battle.

So much for the defended areas. With regard to the great routes that connected them, it has been said they were left undefended. By this is meant that the security of ships pa.s.sing along them was provided for, not by patrols but by escort. The convoy system was adopted, and the theory of that system is that while vessels are on the great routes they are normally liable only to sporadic attack, and they are consequently collected into fleets and furnished with an escort sufficient to repel sporadic attack. In theory, cruiser escort is sufficient, but in practice it was found convenient and economical to a.s.sign the duty in part to ships-of-the-line which were going out to join the distant terminal squadron or returning from it for a refit or some other reason; in other words, the system of foreign reliefs was made to work in with the supplementary escort system.

Where no such ships were available and the convoys were of great value, or enemy's ships-of-the-line were known to be out, similar units were specially detailed for convoy duty to go and return, but this use of battle units was exceptional.

Such a method of dealing with the great routes is the corollary of the idea of defended areas. As those areas were fertile and likely to attract raiding squadrons, so the great routes were infertile, and no enemy could afford to spend squadrons upon them. It is obvious, however, that the system had its weak side, for the mere fact that a convoy was upon a great route tended to attract a squadron, and the comparative immunity of those routes was lost. The danger was provided for to a great extent by the fact that the enemy's ports from which a squadron could issue were all within defended areas and watched by our own squadrons. Still, the guard could not be made impenetrable. There was always the chance of a squadron escaping, and if it escaped towards a critical trade-route, it must be followed.

Hence there were times when the convoy system seriously disturbed our dispositions, as, for instance, in the crisis of the Trafalgar campaign, when for a short time our chain of defended areas was broken down by the escape of the Toulon squadron. That escape eventually forced a close concentration on the Western Squadron, but all other considerations apart, it was felt to be impossible to retain the ma.s.s for more than two days owing to the fact that the great East and West Indies convoys were approaching, and Villeneuve's return to Ferrol from Martinique exposed them to squadronal attack. It was, in fact, impossible to tell whether the ma.s.s had not been forced upon us with this special end in view.

In the liability to deflection of this kind lay the most serious strategical objection to the convoy system. It was sought to minimise it by giving the convoys a secret route when there was apprehension of squadronal interference. It was done in the case just cited, but the precaution seemed in no way to lessen the anxiety. It may have been because in those days of slow communication there could be no such certainty that the secret route had been received as there would be now.

Modern developments and changes in shipping and naval material have indeed so profoundly modified the whole conditions of commerce protection, that there is no part of strategy where historical deduction is more difficult or more liable to error. To avoid such error as far as possible, it is essential to keep those developments in mind at every step. The more important of them are three in number. Firstly, the abolition of privateering; secondly, the reduced range of action for all warships; and thirdly, the development of wireless telegraphy. There are others which must be dealt with in their place, but these three go to the root of the whole problem.

Difficult as it is to arrive at exact statistics of commerce destruction in the old wars, one thing seems certain--that the bulk of captures, which were reckoned in hundreds and sometimes even in thousands, were due to the action of privateers. Further, it seems certain that, reckoning at least by numbers, the greater part of the damage was done by small privateers operating close to their bases, either home or colonial, against coastwise and local traffic. The complaints of merchants, so far as they are known, relate mainly to this kind of work in the West Indies and home waters, while accounts of serious captures by large privateers on the high seas are comparatively rare. The actual damage done by the swarm of small vessels may not have been great, but its moral effects were very serious. It was impossible for the strongest Governments to ignore them, and the consequence was a chronic disturbance of the larger strategical dispositions. While these dispositions were adequate to check the operations of large privateers acting in the same way as regular cruisers, the smaller ones found very free play amidst the ribwork of the protective system, and they could only be dealt with by filling up the s.p.a.ces with a swarm of small cruisers to the serious detriment of the larger arrangements. Even so, the proximity of the enemy's ports made escape so easy, that the work of repression was very ineffective. The state of the case was indeed almost identical with a people's war. The ordinary devices of strategy failed to deal with it, as completely as Napoleon's broadly planned methods failed to deal with the _guerilleros_ in Spain, or as our own failed for so long in South Africa.

By the abolition of privateering, then, it would seem that the most disturbing part of the problem has been eliminated. It is, of course, uncertain how far the Declaration of Paris will hold good in practice. It is still open even to the parties to it to evade its restrictions to a greater or less extent by taking up and commissioning merchantmen as regular ships of war. But it is unlikely that such methods will extend beyond the larger privately owned vessels. Any attempt to revive in this way the old _picaresque_ methods could only amount to a virtual repudiation of statutory international law, which would bring its own retribution.

Moreover, for home waters at least, the conditions which favoured this _picaresque_ warfare no longer exist. In the old wars the bulk of our trade came into the Thames, and thence the greater part of it was distributed in small coasting vessels. It was against this coastwise traffic that the small, short-range privateers found their opportunity and their richest harvest. But, now that so many other great centres of distribution have established themselves, and that the bulk of the distribution is done by internal lines of communication, the Channel is no longer the sole artery, and the old troublesome disturbance can be avoided without a vital dislocation of our commercial system.

The probability, then, is that in the future the whole problem will be found to be simplified, and that the work of commerce protection will lie much more within the scope of large strategical treatment than it ever did before, with the result that the change should be found to tell substantially in favour of defence and against attack.

The reduction of range of action is scarcely less important. In the old days a cruising ship could be stored for six months, and so long as she could occasionally renew her fuel and water, she was free to range the sea outside the defended areas for the whole of the period with unimpaired vitality. For such pelagic operations her movement was practically unrestricted. She could run for two or three days from a superior enemy or chase for as long without loss of energy, and she could wait indefinitely at a likely spot, or change her ground, as danger or hope of plunder dictated. So long as she had men left to man her prizes, her power of mischief was almost unlimited. All this is now changed. The capacity of each cruise of a ship to-day is very small. She is confined to short dashes within a strategically defended area, or if she is bent on pelagic operations, is compelled to proceed so far to find undefended waters that her coal will scarcely permit of more than a few days' actual cruising. A couple of chases at high speed during that period may force her to return at once, subject only to the precarious possibility of renewing her coal from a prize. She has, further, to face the fact that manning prizes must necessarily reduce her capacity for speed, which depends so much on a fully manned engine-room. This will tend to jeopardise her chances of return through or near defended areas. The only escape from this difficulty is to sink the captured ship. But this course has objections scarcely less weighty than the other. No Power will incur the odium of sinking a prize with all hands, and their removal to the captor's ship takes time, especially in bad weather, and the presence of such prisoners in a cruiser in any number soon becomes a serious check on her fighting power. In the case of large ships, moreover, the work of destruction is no easy matter.

In the most favourable circ.u.mstances it takes a considerable time, and thus not only eats into the cruiser's endurance, but decreases her chances of evasion.

From these and similar considerations it is obvious that the possibilities of operations on the great trade-routes are much less extensive than they were formerly, while to speak of cruisers "infesting" those routes is sheer hyperbole. Under modern conditions it is scarcely more feasible than it would be to keep up a permanent blockade of the British Islands. It would require a flow of ships in such numbers as no country but our own can contemplate possessing, and such as could not be maintained without having first secured a very decided preponderance at sea. The loss of radius of action therefore, though it does not increase the power of defence, sensibly lessens that of attack by pelagic operations.

For the great increase in the powers of defence we must turn to the extraordinary development in the means of distant communication. Under former conditions it was possible for a cruising ship to remain for days upon a fertile spot and make a number of captures before her presence was known. But since most large merchantmen have been fitted with wireless installations, she cannot now attack a single one of them without fear of calling down upon her an adversary. Moreover, when she is once located, every ship within wireless reach can be warned of her presence and avoid her. She must widely and constantly shift her position, thereby still further reducing her staying power. On the whole, then, it would appear that in so far as modern developments affect the problem, they certainly render pelagic operations far more difficult and uncertain than they used to be. Upon the great routes the power of attack has been reduced and the means of evasion has increased to such an extent as to demand entire reconsideration of the defence of trade between terminal areas. The whole basis of the old system would seem to be involved. That basis was the convoy system, and it now becomes doubtful whether the additional security which convoys afforded is sufficient to outweigh their economical drawbacks and their liability to cause strategical disturbance.

Over and above the considerations already noticed, there are three others, all of which favour the security of our trade by permitting a much more extended choice of route. The first is, that steam vessels are not forced by prevailing winds to keep to particular courses. The second is, that the improvements in the art of navigation no longer render it so necessary to make well-known landfalls during transit. The third is, that the multiplication of our great ports of distribution have divided the old main flow of trade to the Channel into a number of minor streams that cover a much wider area and demand a greater distribution of force for effective attack. It will be obvious that the combined effect of these considerations is to increase still further the chances of individual vessels evading the enemy's cruisers and to lessen the risk of dispensing with escort.

Nor are the new practical difficulties of sporadic operations on the great routes the only arguments that minimise the value of convoys. We have also to remember that while the number of vessels trading across the ocean has enormously increased since 1815, it is scarcely possible, even if the abolition of privateering prove abortive, that the number of cruisers available for pelagic attack could exceed, or even equal, the number employed in sailing days. This consideration, then, must also be thrown into the scale against convoys; for it is certain that the amount of serious operative damage which an enemy can do to our trade by pelagic operation is mainly determined by the ratio which his available cruiser strength bears to the volume of that trade. This aspect of the question is, however, part of a much wider one, which concerns the relation which the volume of our trade bears to the difficulty of its defence, and this must be considered later.

It remains, first, to deal with the final link in the old system of defence. The statement that the great routes were left undefended will seem to be in opposition to a prevailing impression derived from the fact that frigates are constantly mentioned as being "on a cruise." The a.s.sumption is that they in effect patrolled the great routes. But this was not so, nor did they rove the sea at will. They const.i.tuted a definite and necessary part of the system. Though that system was founded on a distinction between defended terminals and undefended routes, which was a real strategical distinction, it was impossible to draw an actual line where the one sphere began and the other ended. Outside the regularly defended areas lay a region which, as the routes began to converge, was comparatively fertile.

In this region enemies' cruisers and their larger privateers found the mean between risk and profit. Here too convoys, as they entered the zone, were in their greatest danger for fear of their escorts being overpowered by raiding squadrons. Consequently it was the practice, when the approach of convoys was expected, to throw forward from the defended area groups of powerful cruisers, and even battleship divisions, to meet them and reinforce their escorts. Outward-bound convoys had their escorts similarly strengthened till they were clear of the danger zone. The system was in regular use both for home and colonial areas. In no sense did it const.i.tute a patrol of the routes. It was in practice and conception a system of outposts, which at seasons of special risk amounted to an extension of the defended areas combining with a reinforcement of the convoy escorts. Focal points of lesser importance, such as Capes Finisterre and St. Vincent, were similarly held by one or two powerful cruisers, and if necessary by a squadron.

As has been already explained, owing to the peculiar conditions of the sea and the common nature of maritime communications, these dispositions were adopted as well for attack as defence, and the fertile areas, for the defence of which a frigate captain was sent "on a cruise," were always liable to bring him rich reward. His mission of defence carried with it the best opportunities for attack.

In the full development of the system patrol lines did exist, but not for the great routes. They were established to link up adjacent defended areas and as a more scientific organisation of the cruiser outposts. In 1805 the Gibraltar and the home areas were thus connected by a patrol line which stretched from Cape St. Vincent through the Finisterre focal area to Cape Clear, with a branch extending to the strategical centre off Ushant. The new system was introduced at a time when we had reason to expect that the French and Spanish fleets were to be devoted entirely to operations in small raiding squadrons against our trade and colonies. Special provision was therefore necessary to locate any such squadrons that might elude the regular blockades, and to ensure that they should be adequately pursued.

The new lines were in fact intelligence patrols primarily, though they were also regarded as the only means of protecting efficiently the southern trade-route where it was flanked by French and Spanish ports.[24]

[24] It should be said that Cornwallis did not regard this system as new except for the extension from Finisterre to St. Vincent, which Nelson advised. In acknowledging the order from Ushant he wrote, "The instructions ... are nearly the same as have generally been given. I can therefore only guess why a copy of the order was sent to me."--_Admiralty, In-Letters_, 129, 28 September 1805.

The whole system, it will be observed, though not conflicting with the main object of bringing the enemy's fleets to action, did entail an expenditure of force and deflecting preoccupations such as are unknown in land warfare.

Large numbers of cruisers had to be employed otherwise than as the eyes of the battle-squadrons, while the coming and going of convoys produced periodical oscillations in the general distribution.

Embarra.s.sing as was this commercial deflection in the old wars, an impression appears to prevail that in the future it must be much more serious. It is argued plausibly enough not only that our trade is far larger and richer than it was, but also that, owing to certain well-known economic changes, it is far more a matter of life and death to the nation than in the days when food and raw material did not const.i.tute the bulk of our imports. In view of the new conditions it is held that we are more vulnerable through our trade now than formerly, and that, consequently, we must devote relatively more attention and force to its defence.

If this were true, it is obvious that war with a strong naval combination would present difficulties of the most formidable kind, greater indeed than we have ever experienced; for since with modern developments the demand for fleet cruisers is much greater than formerly, the power of devoting cruisers to trade defence is relatively much less.

It cannot be denied that at first sight the conclusion looks irreproachable. But on a.n.a.lysis it will be found to involve two a.s.sumptions, both of which are highly questionable. The first is, that the vulnerability of a sea Power through its maritime trade is as the volume of that trade. The second is, that the difficulty of defending sea-borne trade is also as its volume--that is to say, the larger the amount of the trade, the larger must be the force devoted to its protection. This idea indeed is carried so far, that we are frequently invited to fix the standard of our naval strength by comparing it with the proportion which the naval strength of other Powers bears to their sea-borne trade.

It is hoped that the foregoing sketch of our traditional system of trade defence will avail to raise a doubt whether either a.s.sumption can be accepted without very careful consideration. In the history of that system there is no indication that it was affected by the volume of the trade it was designed to protect. Nor has any one succeeded in showing that the pressure which an enemy could exert upon us through our commerce increased in effect with the volume of our seaborne trade. The broad indications indeed are the other way--that the greater the volume of our trade, the less was the effective impression which an enemy could make upon it, even when he devoted his whole naval energies to that end. It is not too much to say that in every case where he took this course his own trade dwindled to nothing, while ours continually increased.

It may be objected that this was because the only periods in which he devoted his main efforts to trade destruction were when we had dominated his navy, and being no longer able to dispute the command, he could do no more than interfere with its exercise. But this must always be so whether we have positively dominated his navy or not. If he tries to ignore our battle-fleets, and devotes himself to operations against trade, he cannot dispute the command. Whatever his strength, he must leave the command to us. He cannot do both systematically, and unless he attacks our trade systematically by sustained strategical operation, he cannot hope to make any real impression.

If, now, we take the two a.s.sumptions and test them by the application of elementary principles, both will appear theoretically unsound. Let us take first the relation of vulnerability to volume. Since the object of war is to force our will upon the enemy, the only way in which we can expect war on commerce to serve our end is to inflict so much damage upon it as will cause our enemy to prefer peace on our terms to a continuation of the struggle. The pressure on his trade must be insupportable, not merely annoying. It must seriously cripple his finance or seriously threaten to strangle his national life and activities. If his total trade be a hundred millions, and we succeed in destroying five, he will feel it no more than he does the ordinary fluctuations to which he is accustomed in time of peace. If, however, we can destroy fifty millions, his trade equilibrium will be overthrown, and the issue of the war will be powerfully affected.

In other words, to affect the issue the impression made on trade must be a percentage or relative impression. The measure of a nation's vulnerability through its trade is the percentage of destruction that an enemy can effect.

Now, it is true that the amount of damage which a belligerent can inflict with a given force on an enemy's commerce will vary to some extent with its volume; for the greater the volume of commerce, the more fertile will be the undefended cruising grounds. But no matter how fertile such areas might be, the destructive power of a cruiser was always limited, and it must be still more limited in the future. It was limited by the fact that it was physically impossible to deal with more than a certain number of prizes in a certain time, and, for the reasons already indicated, this limit has suffered a very marked restriction. When this limit of capacity in a given force is pa.s.sed, the volume of commerce will not affect the issue; and seeing how low that capacity must be in the future and how enormous is the volume of our trade, the limit of destructive power, at least as against ourselves, provided we have a reasonably well-organised system of defence, must be relatively low. It must, in fact, be pa.s.sed at a percentage figure well within what we have easily supported in the past. There is reason, therefore, to believe that so far from the a.s.sumption in question being true, the effective vulnerability of sea-borne trade is not in direct but in inverse proportion to its volume. In other words, the greater the volume, the more difficult it is to make an effective percentage impression.

Similarly, it will be observed that the strain of trade defence was proportioned not to the volume of that trade, but to the number and exposure of its terminals and focal points. Whatever the volume of the trade these remained the same in number, and the amount of force required for their defence varied only with the strength that could readily be brought to bear against them. It varied, that is, with the distribution of the enemy's bases and the amount of his naval force. Thus in the war of 1812 with the United States, the West Indian and North American areas were much more exposed than they had been when we were at war with France alone and when American ports were not open to her as bases. They became vulnerable not only to the United States fleet, but also in a much higher degree to that of France, and consequently the force we found necessary to devote to trade defence in the North Atlantic was out of all proportion to the naval strength of the new belligerent. Our protective force had to be increased enormously, while the volume of our trade remained precisely the same.

This relation of trade defence to terminal and focal areas is of great importance, for it is in the increase of such areas in the Far East that lies the only radical change in the problem. The East Indian seas were always of course to some extent treated as a defended area, but the problem was simplified by the partial survival in those regions of the old method of defence. Till about the end of the seventeenth century long-range trade was expected to defend itself, at least outside the home area, and the retention of their armament by East Indiamen was the last survival of the practice. Beyond the important focal area of St. Helena they relied mainly on their own power of resistance or to such escort as could be provided by the relief ships of the East Indian station. As a rule, their escort proper went no farther outward-bound than St. Helena, whence it returned with the homeward-bound vessels that gathered there from India, China, and the South Sea whaling grounds. The idea of the system was to provide escort for that part of the great route which was exposed to attack from French or Spanish colonial bases on the African coasts and in the adjacent islands.

For obvious reasons this system would have to be reconsidered in the future. The expansion of the great European Powers have changed the conditions for which it sufficed, and in a war with any one of them the system of defended terminal and focal areas would require a great extension eastward, absorbing an appreciable section of our force, and entailing a comparatively weak prolongation of our chain of concentrations. Here, then, we must mark a point where trade defence has increased in difficulty, and there is one other.

Although minor hostile bases within a defended area have lost most of their menace to trade, they have acquired as torpedo bases a power of disturbing the defence itself. So long as such bases exist with a potent flotilla within them, it is obvious that the actual provision for defence cannot be so simple a matter as it was formerly. Other and more complex arrangements may have to be made. Still, the principle of defended areas seems to remain unshaken, and if it is to work with its old effectiveness, the means and the disposition for securing those areas will have to be adapted to the new tactical possibilities. The old strategical conditions, so far as can be seen, are unaltered except in so far as the reactions of modern material make them tell in favour of defence rather than of attack.

If we desire to formulate the principles on which this conclusion rests we shall find them in the two broad rules, firstly, that the vulnerability of trade is in inverse ratio to its volume, and secondly, that facility of attack means facility of defence. The latter, which was always true, receives special emphasis from modern developments. Facility of attack means the power of exercising control. For exercise of control we require not only numbers, but also speed and endurance, qualities which can only be obtained in two ways: it must be at the cost of armour and armament, or at the cost of increased size. By increasing size we at once lose numbers. If by sacrificing armament and armour we seek to maintain numbers and so facilitate attack, we at the same time facilitate defence. Vessels of low fighting power indeed cannot hope to operate in fertile areas without support to overpower the defence. Every powerful unit detached for such support sets free a unit on the other side, and when this process is once begun, there is no halting-place. Supporting units to be effective must multiply into squadrons, and sooner or later the inferior Power seeking to subst.i.tute commerce destruction for the clash of squadrons will have squadronal warfare thrust upon him, provided again the superior Power adopts a reasonably sound system of defence. It was always so, and, so far as it is possible to penetrate the mists which veil the future, it would seem that with higher mobility and better means of communication the squadronal stage must be reached long before any adequate percentage impression can have been made by the sporadic action of commerce destroyers. Ineffectual as such warfare has always been in the past, until a general command has been established, its prospects in the future, judged by the old established principles, are less promising than ever.