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No. 10.

Report of Major R. Delafield. Views and opinions of Major Richard Delafield, of the corps of engineers, on the following points connected with the defence of the coasts of the United States, called for by the Secretary of War in his communication of the 17th of April, 1851 :

1st. How far the invention and extension of railroads have superseded or diminished the necessity of fortifications on the seaboard ?

No member of the corps of engineers, so far as I am acquainted, has ever considered it expedient to construct permanent fortifications along our seaboard, to defend it against armies operating on the land. The art of fortification, in such an emergency, is principally confined to temporary field-works, thrown up after the enemy has effected a landing, and selected his route of approach.

Such fortifications are only needed to oppose infantry and field artillery, requiring little less than earth for their construction, and executed by the troops in the field, and with a few days' labor.

To the more speedy accomplishment of this particular, in the defence of the nation, railroads have contributed greatly.

Fortifications of a permanent character, requiring a long time to construct and perfect, are, however, considered indispensably necessary to prevent the ingress of the powerful floating batteries that can sail or steam into our harbors, against which railroads can oppose, neither directly nor indirectly, an efficient resistance.

The city of New York, for example, is within three hours’ sail of the ocean. Ships-of-war of the heaviest class, and war steamers with troops, can come to the docks of this city, or lay at anchor in the East and North rivers, and do as much injury and destruction as may suit an enemy's purpose. Now, although several railroads centre in this city from distant and most populous sections of our country, they can bring nothing to prevent the entrance of a maritime force. No number of men that can be concentrated in New York, or along the shores of the water approaches, however well disciplined they may be, can oppose, with any probability of success, the passage of a hostile fleet from the sea to the city, or prevent its destroying its mercantile marine and real estate. Field artillery, infantry, cavalry, and riflemen can have no effect upon ships-of-theline; and the increase of numbers would but swell the loss of our citizens by uselessly exposing them to a ship's broadsides.

The many thousands of uniformed militia that could, within forty-eight hours, be concentrated by railroad and river steamers in New York and its vicinity, could do positively nothing in arresting a hostile fleet from destroying the city.

It will be asked, then, are railroads of no value or use in the defence of the sea-coast? Most certainly, they are a valuable auxiliary; economizing time and treasure, and preventing many a predatory expedition that an enemy might otherwise undertake.

Landings for supplies of provisions, water, or for any hostile purpose against all the cities and towns of the Union, are rendered much more difficult and hazardous to an enemy. Ere he can effect a landing, march to the city, and destroy or lay it under contribution, the railroads and river steamers could transport from hundreds of miles the uniform militia of the country in far greater numbers than any fleet can be expected to bring across the ocean; provided, we can cause such landings to be made at such a distance from the cities as to give time for the railroads and steamers to transport the militia after they are assembled. In all such landings an enemy can have no other description of force than we can bring to oppose him. He has, in such case, been compelled to leave his heavy battering ships.

But so long as he could reach the cities in his ships, he never could throw the advantage in our favor by landing, unless the distance to march was within a few hours' march of his landing.

There is, then, no other permanently reliable, economical, and efficient means of preventing the approach and entrance into our harbors of these ships' batteries, whether sailing or steam, than by opposing them with similar and superior batteries, and compelling the ships to fight the batteries by temporary obstructions in the channels, locating these batteries at the greatest distance that can be found to protect the channels. Such batteries are but fortifications. In their construction we must arrange them for the heaviest class of guns, to secure their action at the greatest distance, and to produce the greatest injury to ships-of-the-line or steamers.

That the troops manning these batteries may not be exposed to the ships' fire, they must be covered in front by earth or masonry, and either placed so high that from a ship's deck, thirty feet above water, they cannot be looked into, or else must be covered over head to secure the gunners. Where the site is not naturally high enough for this purpose, we gain it by masonry, which introduces the construction known as a casemated battery. Once forced to this mode of construction, economy prompts us to put tiers of guns over each other.

But these batteries, however well calculated to protect the men at their guns, must be enclosed in the rear ; otherwise, the marines of a fleet could land, pass into them and drive the artillerists from their guns.

This makes an enclosed battery or fortification, and upon these alone can we depend to protect our harbors, cities, dock yards, &c., economically and efficiently.

These enclosed works must be of such a nature that there shall be no one point outside that cannot be seen from some point within, of such a height that they cannot be scaled by an active and disciplined force, and so strong that field artillery cannot destroy them, which gives time for the militia of the country to march to their relief, and force back any troops that may have landed to take them.

The great change brought about by railroads and river steamers in our sys. tem of defence is in lessening the artificial strength of the land defences of the sea-coast fortifications. Just after the war of 1812 to 1815, it was considered necessary to give them such strength as to require as many days for their reduction as would suffice for assembling the militia in mass and marching to the relief of the forts.

The time of taking a well-constructed fort, properly defended, is a matter of calculation, when its strength is such as to compel the forms of a siege. The basis of this calculation is the excavation and removal of a given quantity of earth, and the landing, mounting, and serving a given number of heavy guns. The guns are

be mounted on the edges of the ditches of the forts, and this can only be done by what is termed zigzag approaches, constituting a siege. At the period above referred to, there were few positions in the United States that did not allow time for an enemy to land, and take, in the above manner, an ordinary bastioned front, ere the militia of the country could come to its relief in sufficient uumbers to contend with disciplined forces.

But at the present time we have but to fulfil the condition of strength on the land side to resist a coup de main or escalade, thereby forcing an enemy to bring up a battering train for its reduction, and we gain the time necessary for its relief. We now need uo second line of defence—a simple flanked scarp, corered with earth, suffices. Herein is the great difference brought about by rail

. roads, that of reducing the magnitude and expense of the land defences of the sea-coast batteries. But the power of the batteries themselves, it will be seen hereafter, must be stronger than ever.

2d. In what manner and to what extent the navigation of the ocean by steam, and particularly the application of steam to vessels-of-war, and recent improve

ments in artillery and other military inventions and discoveries affect this question ?

The navigation of the ocean by steam has had a great influence upon the defence of our seaboard. “The heavy armament of war steamers, their ample storage and accommodation for troops, the rapidity of their evolutions and facility of transport, altogether constitute them convenient and formidable instruments for offensive warfare, particularly for making a descent upon any line of coast with a powerful army. Since 1815 it has enabled seamen to set the elements at defiance, and this would lead hostile powers to consider us more open to invasion."

Before its introduction, it required an immense marine and long time for preparation ere an enemy could effect an invasion of our shores. The expedition fitted out by England against New Orleans was known by us to be in preparation, for some part of our coast, six months before its arrival. After sailing, it had to rendezvous at Jamaica, (from whence, also, we heard of its concentration,) and again at Ship island, before commencing to disembark. This gave much time for us to prepare. At that date we may be considered as having had six months' notice of an intended expedition.

At the present time, with the aid of steam, the notice comes with the blow; a few days now suffices to invade either Boston, New York, Philadelphia, Baltimore, Norfolk, Charleston, or Savannah, from Bermuda. It is the introduction of steam navigation that has given such an advantage over us, compared with the sailing vessels of 1815.

In 1812 Great Britain considered Halifax a suitable place for her naval depot, and stores for her fleet on our coast. It so continued until a recent date, when they discovered that our proximity by land enabled us to reach and destroy it, beyond their power to prevent it. The consequence has been, that a central point opposite our Atlantic seaboard (Bermuda) has been selected, fortified, and still being fortified with great care and strength, and fitted as a naval depot. To it, already, have all the naval stores been removed from Halifax. It is secure against the power or force we can most readily command, (an army,) and, by fortifications, is secure against any naval armament we are likely to possess.

From this point an army can embark in steamers, and in three days be anchored in our harbors, without any other notice than their coming in sight of our headland, but not long enough to enable us to draw together militia to oppose them. Hence it is that we are comparatively weaker, at this time, by the introduction of steam navigation.

Another important facility to an enemy, and to our disadvantage, is gained by the steamship. Fifteen such vessels as have lately been built will carry an army of ten thousand men, with their munitions, to any point on our Atlantic coast in a given space of time, and without any necessity for other rendezvous than the point of attack. Whereas, some hundred sailing transports would be required for the same army, and no calculation made of their arriving at their destination within days of each other.

The defences of the coast of France and England, on the channel, forcibly illustrate the change effected by ocean steam navigation. England considered herself safe from invasion, by the strength of her channel fleet. France considered herself equally safe, by the fortifications of her harbors. For a long period neither power could injure each other, guarded as they were. The fleets of England made many demonstrations upon the coasts of France, but never effected anything of importance, and Napoleon made a powerful combined demonstration with his army and fleet, and failed by the superiority of the English fleet.

But since steam has risen to its present importance, these two nations are considered as having materially changed their relations of defence.

France, with her preponderating land force, transported by steamers, can readily invade England. The channel fleet of old would no longer be a protection. The statesmen of England, fully aware of this state of things, have for some time past been endeavoring to restore their ascendency.

A channel fleet combined with the aid of fortification, “which experience in war and science can suggest,” (Duke of Wellington to the chief engineers,) is now their reliance, but it is a fleet of steam ships-of-war. Several of their ships-of-the-line have been fitted with screw propelling engines, as an auxiliary power, retaining the sails and their powerful broadsides. The first ship built in the English dock yards of this class is the Sanspareil of eighty-one guns, 2,235 tons; carrying on her lower deck thirty 32-pounders of fifty-six hundredweight, nine feet six inches long; main deck, thirty eight-inch guns of fifty-two hundredweight, eight feet long; quarter deck and forecastle, twenty 32-pounders of twenty-five hundredweight, six feet long, one ten-inch gun of eightyfour hundredweight, nine feet four inches long, with a three hundred and fifty horse-power engine, launched at Davenport in April, 1851. With vessels of this description they hope to retain their ascendency on the water, and protect their ports, in the absence of the fleet, against sudden attacks of an enemy's steamers, by fortifications.

In relation to the application of steam to ships-of-war, up to the building of the above vessel, the problem had not been solved. Not a single steamship had been built calculated to contend with a land battery, or a broadside of a ship-of-the-line. We have not, to this day, an instance of steamers having exposed themselves successfully or for any determined purpose to hostile guns, with the exception of the little English iron steamer Nemesis in the Chinese war, where she accomplished much, but against batteries of no value.

As transports and tow-boats, they have contributed greatly to the success of fleets on the invasion of Algiers by the French under Beaumont; the fleet was towed into position abreast the Algerine batteries by their war steamers. At Vera Cruz they made the same use of their steamers--at Beyrout, on the coast of Syria, although the English had the best of their war steamers, they were only used as tow-boats--taking distant stations in the latter part of the action and shelling the fortification.

The French army that recently operated against Rome was transported from Toulon by steamers, carrying artillery, cavalry, and infantry.

The result, then, of the navigation of the ocean by steam goes to prove a greater necessity than ever for defending our cities, harbors and dock yards by some efficient means, whether by fortifications, steam vessels-of-war, or other means, is yet to be considered.

The next branch of inquiry under this second head is : “In what manner and to what extent has the recent improvements in artillery and other military inventions and discoveries affected this question ?”.

The recent improvements in artillery, I apprehend, are rather the result of calling old things by new names, and thus bringing them afresh into notice, than any substantial advantage.

The use of what is generally called the Paixhan gun is supposed to have produced a great revolution in the sea-coast defence. It is no more nor less than firing hollow shot horizontally, a practice that has prevailed as long as the howitzer has been known (about 1693.) The only difference between the field and siege howitzer and Colonel Paixhan's gun is, that he makes his gun longer, and, by his writings, has caused them to be introduced again on board ships-ofwar, and probably more used for sea-coast batteries.

In our own service we had made use of such long howitzers for sea-coast defence years before Colonel Paixhan gave anything to the public on the subject.

We called them columbiads, many of which are now to be seen on Governor's island, in this harbor, that were in use from 1812 to 1815.

On the ocean the use of hollow shot fired horizontally was made by the Count

De Grasse, off the Chesapeake, during our revolutionary war, and abandoned in consequence of the serious injury caused by the accidental explosion of the shells about the decks.

Since their re-introduction similar results have occurred. The steamer Medea, one of Admiral Stopford's fleet, operating against the Egyptians in 1840, when off Alexandria, was seriously injured by the bursting of a shell that, with five others, had been got on deck for examination; one beam was eplit asunder, the whole deck raised, and every buckhead in the captain's cabin, ward, and gunrooms torn to shreds, and the vessel set on fire.

About the same period (December, 1840,) a similar accident occurred on board the Excellent, the gunnery ship at Portsmouth, on trying some shells after hearing of the accident on board of the Medea. The fuses, in both cases, were metal with screw caps, supposed to be a secure preventive against accidents on board vessels. The use, therefore, of this improvement in artillery, for steamers, and on board ships-of-war is, I conceive, quite problematical, while, on the other hand, its value in the sea-coast batteries is increased by the greater ranges, precision of fire, and facility of causing the explosion about the intended and critical moment.

While such shells fired from ships against stone walls and earthen parapets are harmless, breaking to pieces in the one case, and throwing up a few yards of earth only in the other, the injury to the steamer or ship is far greater than from any other artillery in use.

It may not be amiss, under this head, to show the effect of this species of artillery upon vessels, proving, as I think, very conclusively, the safe reliance we may have in defending our harbors by them if mounted in favorable positions.

The effect of hot shot and shells from these columbiads (I must be permitted to use the American name as of prior invention) against shipping was shown by Captain Hastings, in the service of the Greeks, who, at Salona, in 1826–7, fired not only hot shells, which he substituted for hot shot, as by their weight they broke through both sides of small vessels, but he fired carcasses and shells from 68-pounder guns. During the affair at Salona, he says, by the time he had fired twice, a brig-of-war blew up, owing to a shell exploding in her magazine. An armed transport brig sank forward owing to a shell exploding in her bow, and was set

on fire aft by a hot shell. At Trickere he burnt a brig-of-war with hot shot. During an attack of the Greeks against a monastery at Pinæus, within the straits between Salonis and Megara, and for the relief of Athens, the Turkish pacha opened a battery of five guns upon the Greek steamer Perseverance, two of them long five-inch howitzers, producing considerable effect. One shot struck the carriage of a long 68-pounder and exploded there, another exploded in the counter of the Perseverance and tore out two streaks for a length of six feet, and started out the planking from two adjacent streaks, when the steamer retreated from this dangerous position.

In the attack on the harbor of Tolo, the Greeks directed the fire of 68-pounders' shells on a brig—a shell struck her, exploding in her hull and blew her foremast into the water. They afterwards made an attack upon a Turkish squadron of nine vessels, and opened a fire upon the Turkish admiral's ship, distant about five hundred yards, with hot shells. The second fire of two hot shells from the long guns and two carcasses from carronades, one lodged in the hull of the Turkish commodore, and, reaching the magazine, blew her up. A carcase shell exploded in the bows of a brig next to the commodore; she sank foward, while a hot shell striking her stern, which stood up in shallow water, soon enveloped her in flames. In a few minutes another vessel was on fire, and an Algerine vessel having received a shell, which exploded between decks, was abandoned by her crew.

In the harbor of Patras, the Greeks made an attack upon an Austrian brig loaded for the Turkish army, by opening upon her a fire of shells from 68

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