It follows from these premisses that a naval blockade—or a connected series of blockades—can never be regarded as equivalent to an established command of the sea. At its best it can only achieve a temporary command of the sea in a state of unstable and easily disturbed equilibrium. At its worst, that is when it is least close and least effective, and when the animus pugnandi of the enemy is unimpaired and not to be intimidated, and is therefore ready at all times to take advantage of "an opportunity too tempting to be resisted," it amounts to a state of things in which the "fleet in being" becomes the dominant factor of the situation. It is mainly a psychological problem and scarcely a strategic problem at all to determine when the actual situation approximates to either of these extremes, and the principle embodied in the words bene ausus vana contemnere is the key to the solution of this problem. If the blockaded fleet is merely a fortress fleet, or not even that, as was the Russian fleet at Port Arthur for some time after the first night of the war, and even more after the critical but indecisive conflict of August 10, then it is legitimate, as Togo triumphantly showed, to regard the situation so established as so far equivalent to a temporary command of the sea that military operations, involving the security of oversea transit and the continuity of oversea supply, might be undertaken with no greater risk than is always inseparable from a vigorous initiative in war. But had the Russian naval commanders been inspired—as, perhaps, the ill-fated Makaroff alone was—with a genuine animus pugnandi, they might have perceived that their one chance of bringing all the Japanese enterprises, naval and military, to nought, was by fighting Togo's fleet "to a frazzle," even if their own fleet perished in the conflict. Then the Baltic Fleet, if it had any fight in it at all, must have made short work of what remained of Togo's fleet, and the Japanese communications with Manchuria being thereby severed, Russia might have dictated her own terms of peace. The real lesson of that war is not that a true fleet in being can ever be safely neglected, but that a fleet which can be neglected with impunity is no true fleet in being. It should never be forgotten that the problems of naval warfare are essentially psychological and not mechanical in their nature. Their ultimate determining factors are not material and ponderable forces operating with measurable certainty, but those immaterial and imponderable forces of the human mind and will which can be measured by no standard other than the result. By the material standard so popular in these days, and withal so full of fallacy, Nelson should have been defeated at Trafalgar and Rozhdestvensky should have been victorious at Tsu-Shima.
It is, of course, idle to press the doctrine of the command of the sea and the principle of the fleet in being so far as to affirm that no military enterprise of any kind can be prosecuted across the sea unless an unassailable command of the sea has first been established. Such a proposition is disallowed by the whole course of naval history, which is, in truth, for the most part, the history of the command of the sea remaining in dispute, often for long periods, between two belligerents, the balance inclining sometimes to one side and sometimes to the other, according to the fortune of war. The whole question is in the main one of degree and of circumstances. Broadly speaking, it may be said that the larger the military enterprise contemplated the more complete must be the command of the sea before it can be prosecuted with success and the more certain the assurance of its continuance in unimpaired efficiency until the objects of the enterprise are accomplished. Conversely, the strength, even if inferior, of the fleet in being, its strategic disposition, its tactical efficiency, and, above all, its animus pugnandi must all be accurately gauged by a naval commander before he can safely decide that a military expedition of any magnitude can be undertaken without fear of interference from an enemy's fleet. It was the neglect of these principles that ruined the Athenian expedition to Syracuse. It was equally the neglect of the same principles that entailed the failure of Napoleon's expedition to Egypt and the ultimate surrender of the army he had deserted there. It was the politic recognition of them that, as Admiral Mahan has shown in a brilliant passage, compelled Hannibal to undertake the arduous passage of the Alps for the purpose of invading Italy instead of transporting his troops by sea.
The limits of legitimate enterprise across seas of which the command although firmly gripped is not unassailably established, are perhaps best illustrated by the story of Craig's expedition to Malta and Sicily towards the close of the Trafalgar campaign. This remarkable episode, which has received less attention than it deserves from most historians, has been represented by Mr Julian Corbett in his instructive work on The Campaign of Trafalgar as the masterly offensive stroke by which Pitt hoped to abate, and, if it might be, to overthrow the military ascendency which Napoleon had established in Europe. That view has not been universally accepted by Mr Corbett's critics, but the episode is entitled to close attention for the light it throws on the central problem of naval warfare. Pitt had concluded a treaty with Russia, which involved not merely naval but military co-operation with that Power in the Mediterranean. Craig's expedition was the shape which the military co-operation was to take. It consisted of some five thousand troops, and when it embarked in April 1805 it was convoyed by only two ships of the line in its transit over seas which, for all the Government which dispatched it knew, might be infested at the time by more than one fleet of the enemy.
Here, then, is a case in which the doctrine of the command of the sea and the principle of the fleet in being might seem to be violated in a crucial fashion. But the men who directed the arms of England in those days knew what they were about. Long before they allowed the expedition to start they had established a close and, as they thought, an effective blockade of all the Atlantic and Mediterranean ports in which either French or Spanish warships ready for sea were to be found. Nevertheless we have here a signal illustration of the essential difference between a command of the sea which has been made absolute by the destruction of the enemy's available naval forces—as was practically the case after Trafalgar—and one which is only virtual and potential, because, although the enemy's fleets have for the time been masked or sealed up in their ports, they may, should the fortune of war so determine, resume at any time the position and functions of a true fleet in being. On the strength of a command of the sea of this merely contingent and potential character Pitt and his naval advisers had persuaded themselves that the way to the Mediterranean was open for the transit of troops. Craig's transports, accordingly, put to sea on April 19. But a week before Villeneuve with his fleet had left Toulon for the last time, had evaded Nelson's watch, and passing rapidly through the Straits, had called off Cadiz, and picking up such Spanish ships as were there had disappeared into space, no man knowing whither he had gone. He might have gone to the East Indies, he might have gone to the West Indies, as in fact he did, or he might be cruising unmolested in waters where he could hardly fail to come across Craig's transports with their weak escort of two ships of the line. It was a situation which no one had foreseen or regarded as more than a contingency too remote to be guarded against when Craig's expedition was allowed to start. How Nelson viewed the situation may be seen from his reply to the Admiralty, written on his receipt of the first intimation that the expedition was about to start.
"As the 'Fisgard' sailed from Gibraltar on the 9th instant, two hours after the enemy's fleet from Toulon had passed the Straits, I have to hope she would arrive time enough in the Channel to give their Lordships information of this circumstance and to prevent the Rear-Admiral and Troops before mentioned"—that is Craig's expedition—"from leaving Spithead." In other words, Nelson held quite plainly that had the Admiralty known that Villeneuve was at sea outside the Straits they would not have allowed Craig to start. That Nelson was right in this assumption is proved by the fact that acting on the inspiration of Barham—perhaps the greatest strategist that ever presided at Whitehall—the Admiralty, as soon as they had grasped the situation, sent orders to Calder off Ferrol, that if he came in contact with the expedition he was to send it back to Plymouth or Cork under cruiser escort and retain the two ships of the line which had so far escorted it under his own command. The fact was that if Craig's expedition once passed Finisterre it would find itself totally without the naval protection on which the Admiralty relied when it was dispatched. Villeneuve was outside the Straits no one knew where, and had been reinforced by the Spanish ships from Cadiz. Nelson, whose exact whereabouts was equally unknown to the Admiralty, was detained in the Mediterranean by baffling winds and also by the necessity of making sure before quitting his station that Villeneuve had not gone to the Levant. Orde, who had been blockading Cadiz with a weak squadron which had to retire on Villeneuve's approach, had convinced himself, on grounds not without cogency, that Villeneuve was making for the northward, and had, quite correctly on this hypothesis, fallen back on the fleet blockading Brest, being ignorant of the peril to which Craig was exposed. Thus Craig's expedition seemed to be going straight to its doom unless Calder could intercept it and give it orders to return. However, Craig and Knight, whose flag flew in one of the ships of the line escorting the expedition, passed Finisterre without communicating with Calder, and having by this time got wind of their peril, they hurried into Lisbon, there to await developments in comparative safety, though their presence caused great embarrassment to the Portuguese Government and raised a diplomatic storm. It was not until Craig and Knight had ascertained that Villeneuve was out of the way and that Nelson had passed the Straits that they put to sea again and met Nelson off Cape St Vincent. Nelson had by this time satisfied himself, after an exhaustive survey of the situation, that Villeneuve had gone to the West Indies, and resolved to follow him there as soon as he had sped the expedition on its appointed way. But so apprehensive was he of the Spanish ships remaining at Carthagena, that, inferior to Villeneuve as he was, he detached the "Royal Sovereign" from his own squadron, and placed her under Knight's command. It only remains to add that the expedition reached its destination in safety and that its result was the Battle of Maida, fought in the following year—the first battle in which Napoleon's troops crossed bayonets with British infantry and were beaten by an inferior force. The expedition was also the indirect cause of the Battle of Trafalgar itself, for it was in order to frustrate the coalition with Russia of which it was the instrument that Napoleon had ordered Villeneuve to make for the Mediterranean when he finally left Cadiz to encounter Nelson on his path. Thus was it, as Mr Corbett says, "to prove the insidious drop of poison—the little sting—that was to infect Napoleon's empire with decay and to force his hand with so tremendous a result."
Yet it very nearly miscarried at the outset. Nelson and Barham—between them a combination of warlike energy and strategic insight, without a parallel in the history of naval warfare—both realized the tremendous risks it ran. It may be argued that had Villeneuve gone to the north he would have found himself in the thick of British squadrons closing in on Brest and vastly superior in force. Yet Allemand, who had escaped a few weeks later from Rochefort, was able to cruise in these very waters for over five months without being brought to book. It is true that the destruction or capture of five thousand British troops would not seriously have affected the larger issues of the naval campaign, but it would have broken up the coalition with Russia by which Pitt set so much store, and which Mr Corbett at any rate represents as having exercised a decisive influence on the ultimate fortunes of Napoleon. The moral of the whole story seems to be that competent strategists—for the world has known none more competent and none more intrepid than Nelson and Barham—will not risk even a minor expedition at sea unless its line of advance is sufficiently controlled by superior naval force to ensure its unmolested transit. The principle thus exhibited in the case of a minor expedition manifestly applies with immensely increased force to those larger expeditions which assume the dimensions of an invasion. It was not until long after Trafalgar had been fought, and the command of the sea had been secured beyond the possibility of challenge, that the campaigns in the Peninsula were undertaken—campaigns which ended and were always intended to end, should the fortune of war so decree, in the invasion of France and the overthrow of Napoleon. This opens up the whole question of invasion, which will be discussed in the next chapter.
CHAPTER VI
England has not been invaded since A.D. 1066, when, the country having no fleet in being, William the Conqueror effected a landing and subjugated the kingdom. During the eight centuries and more that have since elapsed, every country in Europe has been invaded and its capital occupied, in many cases more than once. It is by no means for lack of attempts to invade her that England has been spared the calamity of invasion for more than eight hundred years. It is not because she has had at all times—it may indeed be doubted if she has had at any time—organized military force sufficient to repel an invader, if he could not be stopped at sea. It is because she can only be invaded across the sea, and because whenever the attempt has been made she has always had naval force sufficient to bring the enterprise to nought. It is merely a truism to say that the invasion of hostile territory across the sea is a much more difficult and hazardous enterprise than the crossing of a land frontier by organized military force. But it is no truism to say that the reason why it is so much more difficult and more hazardous is that there is no real parallel between the two cases. I assume a vigorous defensive on the part of the adversary assailed in both cases—a defensive which, though commonly so called, is really offensive in its nature. The essential difference lies in this, that two countries which are separated by the sea have no common frontier. Each has its own frontier at the limit of its territorial waters, but between these two there lies a region common to both and from which neither can be excluded except by the superior naval force of the other.