The Influence of Sea Power upon History. Alfred Thayer Mahan
the passes of the Pyrenees, Scipio pushed forward into southern Spain, and fought a severe but indecisive battle on the Guadalquivir; after which Hasdrubal slipped away from him, hurried north, crossed the Pyrenees at their extreme west, and pressed on to Italy, where Hannibal's position was daily growing weaker, the natural waste of his army not being replaced.
The war had lasted ten years, when Hasdrubal, having met little loss on the way, entered Italy at the north. The troops he brought, could they be safely united with those under the command of the unrivalled Hannibal, might give a decisive turn to the war, for Rome herself was nearly exhausted; the iron links which bound her own colonies and the allied States to her were strained to the utmost, and some had already snapped. But the military position of the two brothers was also perilous in the extreme. One being at the river Metaurus, the other in Apulia, two hundred miles apart, each was confronted by a superior enemy, and both these Roman armies were between their separated opponents. This false situation, as well as the long delay of Hasdrubal's coming, was due to the Roman control of the sea, which throughout the war limited the mutual support of the Carthaginian brothers to the route through Gaul. At the very time that Hasdrubal was making his long and dangerous circuit by land, Scipio had sent eleven thousand men from Spain by sea to reinforce the army opposed to him. The upshot was that messengers from Hasdrubal to Hannibal, having to pass over so wide a belt of hostile country, fell into the hands of Claudius Nero, commanding the southern Roman army, who thus learned the route which Hasdrubal intended to take. Nero correctly appreciated the situation, and, escaping the vigilance of Hannibal, made a rapid march with eight thousand of his best troops to join the forces in the north. The junction being effected, the two consuls fell upon Hasdrubal in overwhelming numbers and destroyed his army; the Carthaginian leader himself falling in the battle. Hannibal's first news of the disaster was by the head of his brother being thrown into his camp. He is said to have exclaimed that Rome would now be mistress of the world; and the battle of Metaurus is generally accepted as decisive of the struggle between the two States.
The military situation which finally resulted in the battle of the Metaurus and the triumph of Rome may be summed up as follows: To overthrow Rome it was necessary to attack her in Italy at the heart of her power, and shatter the strongly linked confederacy of which she was the head. This was the objective. To reach it, the Carthaginians needed a solid base of operations and a secure line of communications. The former was established in Spain by the genius of the great Barca family; the latter was never achieved. There were two lines possible, --the one direct by sea, the other circuitous through Gaul. The first was blocked by the Roman sea power, the second imperilled and finally intercepted through the occupation of northern Spain by the Roman army. This occupation was made possible through the control of the sea, which the Carthaginians never endangered. With respect to Hannibal and his base, therefore, Rome occupied two central positions, Rome itself and northern Spain, joined by an easy interior line of communications, the sea; by which mutual support was continually given. Had the Mediterranean been a level desert of land, in which the Romans held strong mountain ranges in Corsica and Sardinia, fortified posts at Tarragona, Lilybaeum, and Messina, the Italian coast-line nearly to Genoa, and allied fortresses in Marseilles and other points; had they also possessed an armed force capable by its character of traversing that desert at will, but in which their opponents were very inferior and therefore compelled to a great circuit in order to concentrate their troops, the military situation would have been at once recognized, and no words would have been too strong to express the value and effect of that peculiar force. It would have been perceived, also, that the enemy's force of the same kind might, however inferior in strength, make an inroad, or raid, upon the territory thus held, might burn a village or waste a few miles of borderland, might even cut off a convoy at times, without, in a military sense, endangering the communications. Such predatory operations have been carried on in all ages by the weaker maritime belligerent, but they by no means warrant the inference, irreconcilable with the known facts, "that neither Rome nor Carthage could be said to have undisputed mastery of the sea," because "Roman fleets sometimes visited the coasts of Africa, and Carthaginian fleets in the same way appeared off the coast of Italy." In the case under consideration, the navy played the part of such a force upon the supposed desert; but as it acts on an element strange to most writers, as its members have been from time immemorial a strange race apart, without prophets of their own, neither themselves nor their calling understood, its immense determining influence upon the history of that era, and consequently upon the history of the world, has been overlooked. If the preceding argument is sound, it is as defective to omit sea power from the list of principal factors in the result, as it would be absurd to claim for it an exclusive influence.
Instances such as have been cited, drawn from widely separated periods of time, both before and after that specially treated in this work, serve to illustrate the intrinsic interest of the subject, and the character of the lessons which history has to teach. As before observed, these come more often under the head of strategy than of tactics; they bear rather upon the conduct of campaigns than of battles, and hence are fraught with more lasting value. To quote a great authority in this connection, Jomini says: "Happening to be in Paris near the end of 1851, a distinguished person did me the honor to ask my opinion as to whether recent improvements in fire arms would cause any great modifications in the way of making war. I replied that they would probably have an influence upon the details of tactics, but that in great strategic operations and the grand combinations of battles, victory would, now as ever, result from the application of the principles which had led to the success of great generals in all ages; of Alexander and Caesar, as well as of Frederick and Napoleon." This study has become more than ever important now to navies, because of the great and steady power of movement possessed by the modern steamer. The best-planned schemes might fail through stress of weather in the days of the galley and the sailing-ship; but this difficulty has almost disappeared. The principles which should direct great naval combinations have been applicable to all ages, and are deducible from history; but the power to carry them out with little regard to the weather is a recent gain.
The definitions usually given of the word "strategy" confine it to military combinations embracing one or more fields of operations, either wholly distinct or mutually dependent, but always regarded as actual or immediate scenes of war. However this may be on shore, a recent French author is quite right in pointing out that such a definition is too narrow for naval strategy. "This," he says, "differs from military strategy in that it is as necessary in peace as in war. Indeed, in peace it may gain its most decisive victories by occupying in a country, either by purchase or treaty, excellent positions which would perhaps hardly be got by war. It learns to profit by all opportunities of settling on some chosen point of a coast, and to render definitive an occupation which at first was only transient." A generation that has seen England within ten years occupy successively Cyprus and Egypt, under terms and conditions on their face transient, but which have not yet led to the abandonment of the positions taken, can readily agree with this remark; which indeed receives constant illustration from the quiet persistency with which all the great sea powers are seeking position after position, less noted and less noteworthy than Cyprus and Egypt, in the different seas to which their people and their ships penetrate. "Naval strategy has indeed for its end to found, support, and increase, as well in peace as in war, the sea power of a country;" and therefore its study has an interest and value for all citizens of a free country, but especially for those who are charged with its foreign and military relations.
The general conditions that either are essential to or powerfully affect the greatness of a nation upon the sea will now be examined; after which a more particular consideration of the various maritime nations of Europe at the middle of the seventeenth century, where the historical survey begins, will serve at once to illustrate and give precision to the conclusions upon the general subject.
NOTE.--The brilliancy of Nelson's fame, dimming as it does that of all his contemporaries, and the implicit trust felt by England in him as the one man able to save her from the schemes of Napoleon, should not of course obscure the fact that only one portion of the field was, or could be, occupied by him. Napoleon's aim, in the campaign which ended at Trafalgar, was to unite in the West Indies the French fleets of Brest, Toulon, and Rochefort, together with a strong body of Spanish ships, thus forming an overwhelming force which he intended should return together to the English Channel and cover the crossing of the French army. He naturally expected that, with England's interests