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magnetic telegraph the intelligence that the enemy has put to sea, and is steering, with his expedition of twenty thousand strong, towards Charleston. The effect is electrical; instantly bodies of armed men heeding the summons would spring up, not from bush and brake, in a single glen, as at the sound of Roderick Dhu's whistle, but from every town and hamlet, mountain side and valley in the land. Harnessing up the iron war-horse, they would hold him, panting on the railway, ready at the word to speed off with them for the appointed place, at the rate of thirty, forty, or fifty miles the hour, according to the emergency.

In the meantime, and without confusion, message is sent by lightning for the look-out steamers and naval forces in the Gulf to proceed towards Savannah, and for those at the north to steer south and look into the Chesapeake for further orders. Or they may be directed to cross the enemy's hause and bring him to action, or cut off his stragglers, or otherwise harass and annoy him.

At the end of three or four days, or it may be a week or more, according to the weather, and the great variety of circumstances that tend to retard the movements of such a force at sea, another of the guarda costa steamers puts into the capes of the Delaware or elsewhere, with the certain intelligence that the enemy is bound for Charleston. Because his rate of sailing is regulated by the speed of the slowest vessel in the fleet, he is yet three days from Charleston at the least.

All our ships-of-war that have returned from cruises, that are just fitting out, or that may happen to be in port, together with the whole coast guard of twentyfive steamers which, at the commencement of the war, were found on hand, may thus appear off Charleston as soon as he: certainly they would be there before he could disembark. And should he be so infatuated as to attempt a landing, it would be practicable for us to have there, in force ready to receive him, an army, with a regiment even of foot, from every State in the Union, except perhaps California and Oregon.

Is it possible that an enemy could be tempted by any inducement whatever to land in such a country, provided with such means of defence, invested with such armed ubiquity, and such powers of concentration ?

Fort Moultrie, which has beleagured an enemy before, and has demonstrated that it can hold a force from sea in check long enough at least for the lightning to go for help, and for steam to come with it, is there to beleaguer him again; and our coast fleet, which we have supposed to be assembled there as a witness to this hypothetical attempt at invasion, would be ready at the bar to receive this discomfited and crippled foe as he attempted to escape. Great would be the disappointment to the country if such a fleet should fail to give an account of such an enemy.

The present system of fortifications seems to have been planned upon the idea that in all wars this country was to stand on the defensive, and that all the energies of the enemy would be directed to siege and invasion.

But in the death struggle, what have we to fear from invasion ? There is no pillar nor post in this country which, like the Paris of France, when it falls, carries the whole political edifice with it. There is no Paris in America. Unlike Europe, the armed occupation of a capital here would be no more than the occupation of any other town by an enemy; unlike Europe, there are no disaffected people in this country for a foe to tamper with. The government is by the people, for the people, and with the people. It is the people. And as for invasion, there would be neither danger to the country, nor its government, nor its institutions. Our free institutions are our best fortifications to protect the country from siege, and the land from invasion. Captivating the minds of his soldiers, the civil and political freedom enjoyed by all in these United States would convert the rank and file of an invading foe into friends. An enemy planting his foot upon our soil could at best hold no more of it than that upon which he actually stands and covers with his guns. If he attempted to move,

in whatever direction he should take up the line of march, the people in front he would find enemies, and those that he left behind, emboldened by his own deserters, would rise up in arms against him the moment his presence was withdrawn from them.

What attempts at invasion did England make during the last war? She was afraid of desertion and the propagandism of republican institutions then. It is true, she made a foray upon Washington, but found a precipitate retreat necessary, and that foray was as barren and empty of military result as a eload without water. She attempted New Orleans, but there she encountered one of those sand-bag or cotton-bag forts, and her hosts fell before it.

In the war of 1812 we were young and feeble; England was at the summit of her power. The difference between the military condition of the two countries was immense; yet upon what point along the seaboard did she attempt invasion? Against what battery did she lay siege ? If in the defenceless state of the country then—a country that had a navy to build, that had yet to plan its system of fortifications, to concentrate means of defence—if, under those circumstances, sieges were not laid nor invasion attempted at any point along an open sea front, with its indentations and windings of six thousand miles—if but with one-third of our present population—if with not one-tenth part of our present military resources, nor not the twentieth of our present powers of concentration, siege and invasion were not attempted then by a most ħaughty and proud foe, is it likely that in case of war now, when she looks upon us as her equal, and at least as her match in everything except in the number of " wooden walls ”is it probable or possible that, with such a power for an enemy now, anything like siege or invasion from the sea would be attempted or thought of?

With a home squadron comprised chiefly of steamers, it would be difficult to conceive how an enemy should so threaten as to make it necessary to establish a garrison of 17,000 or even 10,000 men for six months at Charleston or any one of the ten places named in the report.

The operations of these twenty-five steamers would be mostly confined to our own waters in war, for with want of depots of coal abroad they would be required to return into port at the end of every two or three weeks at least for a fresh supply of fuel.

Now bearing in mind my answer to your first question, and always supposing that one of the principal features in the system of national defence hereafter to be provided for this country is naval supremacy for it in its own waters, my answer to your second question is, with the modifications already proposed, that all needful reliance" for coast defence can be placed on vessels-of-war and of commerce, upon open shore batteries, steam, railroads, and telegraph, ol'R FREE INSTITUTIONS, and such like “substitutes for permanent fortifications."

In reply to your third and last question, as to the expediency of continuing the present system of fortifications on the shores of the northern lakes, I have to remark that, in my judgment, it is neither necessary nor expedient so to do.

As for invasion from that quarter, the difference in political condition between Canada and the United States is an ample fortification for us.

Large bodies of the people there now are known to be in favor either of separation from the mother country or of annexation to the United States.

An American army, therefore, going over into Canada in a war with England would be looked upon by a large number of the people there as friends and deliverers, not as enemies and oppressors.

The last war on the waters of the lakes was a war of ship-building.

Ile who could muster the strongest naval forces there—and there they had to be created—had the supremacy. And if, in case of war now, England should succeed in getting ahead of us with her naval forces on the lakes she eonld inflict great injury. A few days of uninterrupted control there by a few armed vessels, insignificant altogether as to absolute force, would make dreadful havoc

blow in war.

upon our lake shipping, our lake commerce, and our lake towns, if no precautions were taken to guard against it.

The commerce of the lakes will soon be worth to us as much or more than the commerce of the Atlantic.

During the season of lake navigation there is put afloat upon those waters every week, on the average, millions of American property, besides vessels and the lives of American citizens.

In no part of the world, except in the offings and harbors of the great commercial emporiums, is there to be found such a concentration of merchandise afloat. Nor is there, in case of our naval inferiority upon the lakes, any part of the world that affords such an abundant harvest of prizes to tempt the cupidity of seamen.

It is the policy of this country never to be the aggressor; it loves peace and hates war, and therefore it is not likely ever to be the party to strike the first

That is an advantage at which Great Britain generally aims, and that she fully understands and appreciates the importance of striking quickly upon the lakes in case of war with this country we have evidence conclusive.

Before she sent her minister plenipotentiary here with his ultimatum, when the friendly relations between the two countries a few years ago seemed to be so much in danger, she first assembled a fleet of fifty-odd sail in our waters, and upon our frontiers one-third of the whole British army, notwithstanding that she was at that time engaged in two distant and expensive foreign wars.

No one who, calling to mind those times, will examine her military journals of that day can fail to be impressed with the fact that her forces were especially arranged with a view to Canada and the lakes, and that there the first blow, or a blow synchronous with the first, was to be struck. Her intentions then were too manifest to be forgotten or disregarded even now.

It is true the war might commence during the season when the navigation of the lakes is annually closed, and when, consequently, all naval forces would be tied up. In that case we should have nothing to fear. But it might commence in the height of the commercial season; and the war might be commenced on her part by first admitting from the sea a fleet of small-class vessels, passing them up through the Canadian ship-canals into the lakes, and there letting the declaration of her intentions consist in an attack upon Buffalo, Chicago, and other lake towns with their shipping.

These interests are too valuable and important to be left at the mercy of an enemy even for a day. Therefore it would be advisable, so long as Canada is an English colony, to provide against a naval surprise on the lakes.

For this purpose it is only necessary to look to the means of assembling quickly a small naval force on the lakes, and, in the meantime, to place at the several cities and towns, and at the termini of the various railroads and canals along the lake shores, a few pieces of ordnance, according to the plan suggested for the towns generally along the Atlantic seaboard.

The forts which are already on the lakes need not be garrisoned in war only until we acquire the naval supremacy there.

We have canals and railroads by which we could send the frames of vessels and all requisite naval means to the lakes at short notice and in time to re-enforce what we might suddenly assemble there.

It seems, therefore, that, acting upon the policy of so shaping our system of national defence as to secure the naval supremacy in our own waters, we should proceed to build the engines, provide the armaments, and get out at the navy yards of Memphis and New York the frames of a few small men-of-war steamers for the lakes. The engines and the armaments might be placed upon the lake shores at once. The frames, on the first appearance of the war cloud, could be sent there by the Erie and the Michigan canals, put together, and be ready for launching at a moment's warning.

The Mediterranean is an inland sea, so are our lakes and rivers. Eminently continental in its proportions and maritime in its features, our country looks out upon blue water to the east, the south, and the west; the ocean front of the United States alone is greater in extent than the ocean front of the whole of Europe. Therefore, like action to the orator, a navy to us is the first, second, and third chief requisite to any effective system of national defence. Respectfully, &c.,

M. F. MAURY,

Licutenant United States Nary. Hon. CHARLES M. CONRAD,

Secretary of War.

No. 7.

Report of Lieutenant J. A. Dahlgren.
ORDNANCE OFFICE, UNITED STATES Navy YARD,

Washington, September, 1851. Sir: I had the honor to receive a communication from the honorable Secretary of the Navy, enclosing certain queries from yourself in relation to the defences of the United States coast, with directions to “ give to the subject my best reflections, and communicate the result to the Secretary of War.” I have complied with the directions of the honorable Secretary of the Navy, as far as permitted by the limited time allowed for the purpose, and now beg leave, very respectfully, to lay before you such facts and opinions as have a bearing on the subject-matter of the queries proposed.

Query 1.– To what extent, if any, ought the present system of fortifications for the protection of our seaboard to be modified, in consequence of the application of steam to vessels-of-war, the invention or improvement of projectiles, or other changes that have taken place since it was adopted in the year 1816?

Shells projected horizontally from cannon are most destructive agents when used against shipping, but are not so efficacious against the masonry of regular works as shot, though in entering an embrasure and bursting they might do considerable mischief.

So far, therefore, as casemated batteries are concerned, shells have added very little to the power of ships ; but against guns en barbette they will be found of material assistance, especially if charged with balls and used as shrapnel. And against open works, the concentration afforded by the wellserved broadsides of one or more ships, should suffice to silence the works, if the vessels have no unusual disadvantages to encounter, and are brought within sure distance.

On the other hand, shells are exceedingly destructive to vessels if exploded in their sides; but as land works already possess, in shot, especially when heated, superabundant means for destroying ships that will expose themselves long enough to their fire, it may, on the whole, be deemed fairly doubtful whether, in a general view, the introduction of shells has materially altered the relations of fort and ship when opposed to each other.

If the question between them were merely the relative capacity, so far as attack and defence were concerned, there would be no difficulty in solving it. But in the great majority of cases, where the sea defences of the United States are concerned, the true question is in regard to the capacity of ships to endure the fire of forts long enough to pass them without so much injury as to interfere with the subsequent operations.

And it is on this account that the application of steam is to be considered as materially affecting the power of forts. For whether it be used as a chief motive power or as an auxiliary, it gives great facility in concentrating and appearing suddenly on given points, and in assuring a certain and rapid transit when required to pass the fire of a fort.

În the defence of nearly every one of the large commercial cities, it will be observed that the chief reliance to prevent the approach of an enemy is by fortifying some approach to it; the naval question merely touches the practicability of passing the fire of these works, and not of sustaining it any longer than may be necessary in the most rapid movement that the ship is capable of.

To illustrate this practically let us turn to the mode proposed in the engineer's report* for excluding an enemy from the lower bay of New York by a fort on Sandy Hook, with floating batteries and bomb ketches inside.

The ordnance commonly mounted in the coast fortifications are 32-pounders, 42-pounders, and eight-inch howitzers. The effective fire of the 32-pounder can hardly be said to extend beyond a mile where heavy ships are concerned.

At that distance the penetration will not exceed fourteen inches when the shot strikes the surface fairly and directly. If the impact be oblique or on ricochet, the penetration is decreased accordingly. The effect of the fire is further decreased by the unavoidable deviation of shot at the distance of a mile, and by the movement of the object which is changing its position in direction and distance. It would be difficult to estimate correctly the number of shot which would have a maximum penetration under these circumstances, but perhaps not more than one in ten. The forty-two pounder and army eight-inch howitzer will not vary this capacity considerably, and it seems reasonable to assume that, if the distance be greater than a mile no material injury will be experienced from such pieces by a heavy ship when under way.

The sketch annexed represents the localities in question as given by the chart of the Coast Survey. The track at mean low water allowed to the heaviest steamerst is shown by the coloring.

The effective fire for the proposed fort as indicated by the circle, evidently covers no considerable part of the passage, and if a steamer chose to take the main channel she would, by keeping its extreme right, be under fire about six or seven minutes, and never approach the guns of the fort nearer than fourteen hundred yards, thus rendering the chances of any damage exceedingly slight. But the wash channel offers sufficient depth for her draught, and by using it the steamer would pass entirely out of reach of the fort. The sole reliance, then, to exclude the fleet becomes the floating batteries and bornb ketches ; whether they may be trusted or not will be cons dered subsequently; the present object is merely to inquire if the fort has the power of itself to exclude shipping.

It seems evident, therefore, that while it is very doubtful whether forts have gained any advantage from the use of shells, it is certain their efficacy has been considerably diminished by the application of steam to the vessels-of-war, which by their decreased draught are enabled to enter channels not accessible to ships-of-the-line, and when obliged to pass the fire of permanent works are enabled to do so in so little time as hardly to afford the batteries an opportunity to effect any essential damage.

Query 2.-What reliance could be placed on vessels of war or of commerce, floating batteries, gunboats, and other temporary substitutes for permanent fortifications ?

In proceeding to answer this query, I find the ground already occupied by certain propositions contained in an official document drawn up in 1840 in relation to the defences of the coast. The source from which these views emanate and their official character entitle them to full consideration, so that I do not

• To War Department, 1840.
† Susquehanna, full loaded, draws nineteen feet eleven inches.

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