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on them exclusively. In such a case, the enemy should be stopped by some physical impediments; and the batteries must be strong enough to prevent his removing these impediments, and also to prevail in a cannonade, should the enemy undertake to silence the works.

The conditions these obstructions have to fulfil are these:

1st. They must be of a nature to be fixed readily, and to be speedily removed when there is no longer occasion for them; and, to this end, they must be afloat.

2d. They must have adequate inertia to resist, or rather not to be destroyed or displaced by, the shock of the heaviest ship; and, in order to this, they must be held by the heaviest and strongest cables and anchors.

3d. They must be secure from the effects of explosive vessels; and, if in danger from this source, must be covered as above mentioned.

We do not say what are the exact circumstances in which all these conditions will be fulfilled, though we think the idea long ago presented by the board of engineers will, with modifications, embrace them all.

The idea is this: Suppose a line (extending across the channel) of rafts, separated from each other by a space less than the breadth of a ship of war, each raft being about 90 feet long, 30 feet wide, and 6 feet deep, formed of strong timbers, crossed and braced in all directions, and fastened together in the strongest manner. A long-scope chain cable is to proceed from each of the four corners, two obliquely up-stream, and two obliquely down stream, to very heavy anchors; and there should also be a very strong chain cable passing from one raft to another. Suppose a ship, striking one of the rafts, to break the chains leading down the stream: in doing this, she must lose much of her momentum. She has, then, "under her fore foot," the raft connected by a strong chain with the rafts to the right and left; on being tightened, this chain will throw the strain upon the down stream cable of that adjoining raft towards which the ship happens to tend. If we suppose it possible for these chains also to be parted, by the power still remaining in the ship, or by impulses received from succeeding vessels, there will be other chains still to break in the same way. After the down-stream chains are all parted, the rafts will "bring up" in a new position, (higher up the channel,) by the anchors that, in the first instance, were pointed up stream. Here a resistance, precisely like that first overcome, is to be encountered by vessels that have lost most of their force in breaking the successive chains, and in pushing these great masses of timber before them through the water. Should there exist a doubt as to the sufficiency of these remaining anchors and chains, or should it be deemed most prudent to leave nothing uncertain, a second similar line may be placed a short distance above the first.

The best proportions and dimensions of the rafts remain to be determined; but as there is scarcely a limit to the strength that may be given to the rafts themselves, and to the means by which they are to be held to their positions and to each other, the success of a well-arranged obstruction of this sort can hardly be doubted.

The expense would not be great in the first instance, and all the materials would be available for other purposes, when no longer needed for this. It may be repeated here, that such expedients need not be resorted to, except to cover objects of the highest importance and value, such as would induce an enemy to risk a large expedition. For objects of less importance, batteries would afford ample protection. It will be remembered that this last power is, when once established in any position, a constant quantity; and, although

it should be incompetent to effect decisive results when diffused over a large fleet, may be an overmatch for any small force upon which it should be concentrated. At the same time, therefore, that there is the less liability to heavy attacks, there will be, in the batteries, the greater capacity of resist. ance to others.

It must not be urged, as a reproach to fortifications, that, in the case we are considering, they are obliged to call in aid from other sources, so long as these aids are cheap, efficient, and of easy resort. By the mode we have suggested, the defence will undoubtedly be complete, every chance of success being on the side of the defence; that is to say, if any confidence is to be placed in the lessons of experience. How, on the other hand, will the same security be attained by naval means? Only, as before shown, by keeping within the harbor a fleet, or squadron, or whatever it may be, which shall be at all times superior to the enemy.

In a naval defence, there will be no advantage in obstructions of any sort, for there can be no lessening of the array of guns, in consequence of such obstructions; because, if these obstructions are under the fire of the floating defences, the enemy will first subdue that fire, and then remove the obstructions at his leisure. If this fire prove too powerful for the enemy, the obstructions will have been unnecessary, and will serve only to shut up our own fleet, preventing the prompt pursuit of a beaten foe.

4. There is a fourth class; consisting of harbors, or rather bays or estuaries, of such expanse that batteries cannot be made to control the passage. These have been before spoken of. If the occupation of, or passage through, these must be defended, it must be by other means than batteries upon the shore. The reliance must, from the nature of the case, be a floating defence, of magnitude at least equal to the force the enemy may bring. The complete defence of each of these bays would, therefore, involve very great expense; certainly, in most cases, greater than the advantages gained. The Chesapeake bay cannot, for instance, be shut against a fleet by fortifications; and if the entrance of the enemy is to be interdicted, it must be by the presence of a not inferior fleet of our own. Instead of such a system, it will be better to give up the bay to the enemy, confining our defences to the more important harbors and rivers that discharge into the bay. By this system, not only will these harbors be secure, but the defences will react upon the bay itself, and, at any rate, secure it from predatory incursions; because, while Hampton roads and the navy-yard at Norfolk are well protected, no enemy would proceed up the bay with any less force than that which could be sent out from the navy-yard.

In certain cases of broad waters, wherein an enemy's cruisers might desire to rendezvous in order to prosecute a blockade, or as a shelter in tempestuous weather, there may be positions from which sea-mortars can reach the whole anchorage, although nothing could be done with guns. A battery of sea-mortars, well secured from escalade, would, in such a case, afford a good defence; because no fleet will lie at anchor within the range of shells.

In thus distributing the various exposed points of the seacoast into general classes, according to the most appropriate modes of defence, we do not find that any thing can be substituted for fortifications, where fortifications are applicable; and we find them applicable in all the classes but the last; and in the last we shall find them indispensable as auxiliaries. In this last class, there are, no doubt, some cases where naval means must constitute the active and operative force; and it is probable that steam batteries may, of all floating defences, be the most suitable,

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It must not be forgotten, however, that the very qualities which recommend this particular kind of force will equally characterize the steam-vessels of the enemy; nor must it be forgotten that, whether steam-vessels, or sailing vessels, or both, are relied on, unless there are well secured points on the shore, under which they can take refuge, they will themselves constitute an object inviting the superior force of an enemy.

'If, for example, we were to deem one of the open harbors of such importance as to assign eight or ten steam batteries for its protection, we should thereby place within reach of the enemy an object worthy of the efforts of a squadron, or twelve or fifieen vessels of the same description. Even, there. fore, in the cases where naval means must be resorted to for defence upon the water, there should be works upon the shore, behind which, if overpowered, they can retire.

It has been before remarked, that the steam batteries are in no way more formidable to shore batteries than sailing vessels are: armed with Paixhan guns, they would be less so. And they would be less formidable, also, on account of their comparatively small number of guns; for there is no reason why the firing should be more accurate than from ships; and the chances of inflicting injury would be in proportion to the number of missiles.

The only material effect the introduction of this description of vessel can have upon a system of defence by fortifications, is, that, owing to their less draught of water, it will be necessary to secure channels that, not being navigable by vessels of the line and frigates, might otherwise be left unguarded. Some of these channels may have the draught of water lessened by an artificial ridge of stones, so as to be impracticable even to steam-vessels; and this may often be done at small expense, and without detriment to the harbors; others will need additional fortifications. But the instances are not numerous where any such shallow channels exist.

In opposition to an opinion not uncommon, that modern improvements in steam-vessels will tend to lessen the necessity for fortifications, we here see that the tendency is rather to increase their number.

Thronghout this whole discussion, the argument has turned on the relative efficiency of fixed and floating defences. The great relative economy of the former, we suppose, will be conceded. If not, we would ask, as conclusive, or at least as leading to calculation entirely satisfactory, that the following information be obtained from authentic sources, namely: the first cost, when complete in all respects, of the frigates United States, Constitution, and Congress, and also the entire expense of each of said vessels up to this time; specifying, as to each, the year of the several expenditures and the amounts thereof, under the heads, as far as practicable, of first cost, repairs or rebuilding, and improvements and alterations; and distinguishing-1st. The expense bestowed upon the hull. 2d. The expense bestowed upon the masts, spars, sails, anchors, cables, and rigging. 3d. The expense bestowed upon the armament; and 4th. The expense bestowed upon all other matters, (as boats, ballast, tanks, paint, &c.) necessarily connected with the preservation, or the ordinary service of the vessel.

Before we proceed to describe the several positions on the coast requiring fortifications, we have something still to say on the general subject, though on another branch. We now refer to the kind of fortifications, or rather to their magnitude and strength. That this particular topic should be embraced by our remarks, is the more necessary, since views hostile to the system of works now in progress have been urged from a high source.

The present system is founded on this principle, to wit: that the fortifications should be strong, in proportion to the value of the objects to be secured. The principle will not, we suppose, be controverted, but only the mode of applying it.

There will hardly be a difference of opinion as to the mode of guarding the less important points. There being no great attraction to an enemy, works simple in their features, requiring small garrisons only, containing a moderate armament, but at the same time inaccessible to the dashing enterprises that ships can so easily land, and which can be persevered in for a few hours with much vigor, will suffice. Circumstances must, however, materially modify the properties of these works, even when the points to be guarded are of equal value. In one, the disadvantage of position must be compensated by greater power; in another, natural strength may need little aid from art; in another, greater width in the guarded channel may demand a larger armament; and in a fourth, peculiar exposure to land attack may exact more than usual inaccessibility. But all these varieties lie within limits that will probably be conceded.

As to the larger objects, it has been contended that there has been exaggeration in devising works to cover these-the works having been calculated for more formidable attacks than they will be exposed to. It is easy to utter vague criticisms of this nature; and it is not easy to rebut them, without going into an examination as minute as if the criticism were ever so precise and pertinent.

But let us look a little at the material facts. What is the object of an enemy? What are his means? What should be the nature of our defences? The object may be to lay a great city under contribution, or to destroy one of our naval depots, or to take possession of one of our great harbors, &c. It was estimated that in the great fire in the city of New York, in the year 1835, the property destroyed within a few hours was worth upwards of $17,000,000, although the fire was confined to a very small part of the city, and did not touch the shipping. Is it easy, then, to estimate the loss that would accrue from the fires that a victorious enemy could kindle upon the circuit of that great city, when no friendly hand could be raised to extinguish them? or is it easy to overrate the tribute such a city would pay for exemption from that calamity? Can we value too highly the pecuniary losses that the destruction of one of the great navy-yards would involve? and the loss, beyond all pecuniary value, of stores and accommodations indispensable in a state of war, and that a state of war can hardly replace?

But what are the enemy's means? They consist of his whole sea-going force, which he concentrates for the sake of inflicting the blow. In the language of the critic: "From the nature of maritime operations, such a fleet could bring its whole strength to bear upon any particular position, and, by threatening or assailing various portions of the coast, either anticipate the tardy movements of troops upon land, and effect the object before their concentration, or render it necessary to keep in service a force far superior to that of the enemy, but so divided as to be inferior to it on any one point."

We have, then, objects of sufficient magnitude; and the means of the enemy consist in the concentration of his whole force upon one of these objects.

With the highest notion of the efficiency of fortifications against shipping, these are not cases where any stint in the defensive means are ad

missible. Having, therefore, under a full sense of the imminent danger to which the great objects upon the coast are exposed, applied to the approaches by water an array of obstacles worthy of confidence, we must carefully explore all the avenues by land, in order to guard against approaches that might be made on that side, in order to evade or to capture the works guarding the channels. But, before deciding on the defences necessary to resist these land attacks, it will be proper to estimate, more particularly, the means that an enemy may be expected to bring forward, with a view to such land operations.

History furnishes many examples; and the expedition to Flushing, commonly called the Walcheren expedition, may be cited as peculiarly instructive.

From an early day, Napoleon had applied himself to the creation of a maritime force in the Scheldt; and, in 1809, he had provided extensive dock-yards and naval arsenals at Flushing and at Antwerp. On his invasion of Austria this year, he had drawn off the mass of his troops that had before kept jealous watch over these naval preparations; relying now on forts and batteries, and on the fortifications of Flushing and Antwerp, for the protection of the naval establishments, and of a fleet containing several line-of-battle ships and frigates, and a numerous flotilla of smaller vessels.

The great naval establishment at Flushing, near the mouth of the Scheldt, and of Antwerp, some sixty or seventy miles up the river, with the vessels afloat on the river, or in progress in the yards, presented an object to England worthy of one of her great efforts.

The troops embarked on this expedition consisted of upwards of 33,000 infantry, 3,000 cavalry, more than 3,000 artillery, and some hundreds of sappers and miners; constituting an army of about 40,000 men. The naval portion consisted of 35 sail of the line, 23 frigates, 33 sloops of war, 28 gun, mortar, and bomb vessels, 36 smaller vessels, and 82 gun-boats: making a total of 155 ships and other armed vessels, and 82 gun-boats. The guns, mortars, &c., provided for such bombardments and sieges as the troops might have to conduct, amounted to 158 pieces, with the suitable supplies of ammunition and stores of every kind.

The idea of sailing right up to their object, in spite of the forts and batteries, seems not to have found favor, notwithstanding the power of the fleet. The plan of operations, therefore, contemplated the landing a portion of the army on the island of Walcheren, to carry on the siege of Flushing; while another portion proceeded up the Scheldt as high as Fort Bartz, which was to be taken; after which, the army would push on by land, about twenty miles farther, and lay siege to Antwerp: all which, it was thought, might be accomplished in eighteen or twenty days from the first landing.

The execution did not accord with the design. Flushing, it is true, was reduced within fifteen days; and in less than a week from the debarcation, (which was on the 31st of July,) Fort Bartz was in possession of the English, having been abandoned by the garrison. But it was twenty five days before the main body, with all necessary supplies for a siege, were assembled at this point, and ready to take up the line of march against Antwerp. Since the first descent of the British, matters had, however, greatly changed. The French were now in force; they had put their remaining defences in good condition; they had spread inundations over the face of the coun

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