The question of our national defense, always a difficult one, is now complicated by financial stringency, which imposes upon Congress a rigorous economy, while the construction and arming of forts and war ships necessarily demand an enormous expenditure.

Yet the nation must be prepared for defense as soon as possible, for no one can say when we may have to take up a gage of battle. Is it, therefore, possible to devise a secondary system of defense, which can strengthen without supplanting our primary system, and can be rapidly developed at a very moderate cost, and yet be of sufficient power to afford defense to our most exposed points until enough of time and treasure may be expended to bring to completion our permanent defensive system, of which the powerful work at Sandy Hook is so magnificent an example?

As a partial answer to this question, the following suggestions are submitted, as containing matter not unworthy of consideration, with the claim that the facts and principles relied on are well known, and are manifested in the daily routine of civil and social life.

The problem of closing waterways by artillery fire alone, since the application of steam and armor to ships of war, has proved a very difficult one, as has been frequently demonstrated, notably by us during our civil war, when the passage of the Mississippi River was forced by the Union’s wooden ships at its lower forts, at Port Hudson and Vicksburg; and while the defenders there had neither the formidable guns, explosives, or projectiles, nor the appliances for securing accuracy of fire, of to-day, yet neither were they opposed by ships as strongly armored or armed, or as swift, as are those ships which now might assail or attempt to run by our new forts. A further evidence of the inability of forts to protect waterways by artillery alone has been recently furnished by the facility with which Mello’s ships passed in and out of port at Rio de Janeiro in defiance of the three formidable forts at its entrance.

But suppose hostile ships of war should run past a fort, or suppose the fire of the hostile navy should destroy, or even cripple, the fort and its guns, so that the enemy’s fleet passed the fort: is it not well, instead of a calamitous surrender to the enemy, to construct some system, if it be possible, whereby a secondary defense may be brought into operation when artillery fire shall have proved insufficient?

If it were given to Edison or Sir William Thomson, or to other experts, to devise some plan which, without crippling or interfering with the present military systems, but rather coöperating with them, would rely principally upon agencies other than those in common military use, and apply them to the defense of a line say a hundred miles long, or of the area of a circle sixty miles in diameter, the centre of such circle being New York, or any other point selected for defense, it is reasonable to suppose such a plan would indicate the possibility of realizing unexpected and wonderful results. There may be doubts as to what particular plan they would recommend, but there are certain considerations, possibilities, and facts which stand out so prominently that they would be necessarily woven into it.

Of course torpedoes of every kind would be used; and, beside these, a primary consideration would be to use agencies the forces of which could be generated at points so remote from the enemy as to be beyond his power of attack, while at the same time these forces could, with absolute security, be rapidly transferred into positions sufficiently near the enemy to develop their destructive powers, thereby essentially differing from forts or ships, which, in order to attack or defend, must necessarily be brought within the range of the enemy’s power of attack.

Electric currents of enormous energy, capable, under the condition of actual contact, of destroying life in any number of men exposed to it, and possibly ships of war also, can be generated at points thirty miles or more distant from the localities where they are expected to be used, and be transferred there with inconsiderable decrease of power. Inflammable oils can be conveyed through pipes by gravitation, or pumps working, if necessary, twenty miles from point of discharge, and after discharge can be instantaneously ignited whenever desired, and, when discharged upon or under water, will float and burn upon its surface.

Thus, electricity and inflammable oils meet the primary consideration of possessing centres of supply and activity remote from the enemy, and of developing powers capable of almost instantaneous transmission to points where they could operate effectively against an enemy, with a continuous renewal and supply of power; and therefore currents of electricity and inflammable oils, separately or jointly, are well adapted for use in defensive war.

It must be borne in mind that an enemy, when he attacks, must advance upon the defender’s position following certain determinate lines, and encountering such obstacles as the defender may have created on the terrene and waters in his possession.

Owing to our ocean-guarded frontier, only a small interest is felt by us in considering how attacks made upon land may be repelled; and therefore only a few suggestions will be made showing how electricity and inflammable oils can be used for defense upon land.

It is self-evident that no rampart could be scaled, no fortress stormed, no lines or intrenched positions carried, by troops suddenly brought into actual contact with continuous alternating electric currents of 1400 volt power or more; or by troops required to cross a ditch, or area of ground, sheeted with or spouting inflammable oil, capable of being ignited at the moment of actual combat.

It may be said that the electric wires could be rendered harmless by bodies of troops protected by non-conducting armor, or provided with non-conducting cutting appliances; but when it is considered that the wires would be under the guns of the defenders, that every contrivance that could be suggested would be used to multiply and even renew wires, to raise them unexpectedly, to project them into position repeatedly during the attack, it may be assumed that the electric current could, by some one of many devices, overmaster the counter-defense, and successfully develop its own power. In addition it must be considered that the electric current could and ought to be used in union with other agencies, and especially with inflammable oils brought in continuously flowing streams or spouting jets to selected points of anticipated attack, and ignited at any opportune moment.

It may be further objected that the apparatus for electric defenses and inflammable oil would be too complicated and troublesome for practical use; but it cannot be denied that the electric current and the oil can be readily and safely brought to desired points, and that the agencies to employ either are as simple as those required for rockets and torpedoes, for the gun-carriages of heavy artillery, for loading, manœuvring, and firing heavy guns, and especially more simple than the complicated machinery designed for fighting heavy guns in movable or even fixed turrets in ships of war.

If, then, it be sought to work out a plan whereby a line one hundred miles long could be defended with few men and great effectiveness, it may be assumed, as is the fact in the United States and Europe, that lines of commercial railways, with rare exceptions, constitute strategic lines; and that if a continuous belt of land, say six miles wide, of which belt the said railways form the centre, could be successfully held, all the conditions of war would be absolutely dominated and controlled by those who hold and possess such continuous belt of land.

If continuous belts of land, six or even four miles wide, could be securely held by fortifying railways with mobile armament, the military effect would be the same as if a deep and navigable river, four or six miles wide, covered with the defender’s ships of war, were encountered by an enemy destitute of ships.

It is to be noted that this system does not contemplate the fortifying of only a single line of railway, but of all those over which the advance of an enemy must cross; and hence when, as in most of the civilized countries, lines of railways approximate each other on nearly parallel or inclined lines, and especially when they cross, all should be armed with batteries, whereby the defensive power of each would be greatly intensified, as the enemy must assault a network of fortified lines, and expose himself to front, flank, and rear fire.

So numerous are railway lines that in civilized countries no battles can be fought away from them.

In the Franco-Prussian war of 1870, all the battles were fought so near to railways that their result would have been controlled if such railways had been fortified and held by properly constructed batteries.

In England, no invading army could even camp without crossing several lines of railways, which, if equipped with mobile batteries, would hold an invading army in a state of siege before it could deploy itself. Most of the great battles of our civil war were fought along or near railway lines, and it was at the battle of Savage Station, near Richmond, that, for the first time in actual war, General Lee used an ironclad railroad battery moving on and fired from a commercial railway; but a single battery can effect no more than a single link in a chain.

Armored and unarmored batteries, probably costing not more than a section of horse artillery, can be placed upon the railways and be moved thereon with great celerity, can be armed with guns far heavier than any that can be readily transported over roads by animal power, and can be made absolutely inexpugnable by means of machine guns and many other known and effective instrumentalities, and by proper support. Many facts confirm these assertions, and amongst them the experience of actual war, the firing of even the heaviest guns from rails at most of the official tests, and the frequent transportation by railways of the heaviest guns, notably of the 124-ton Krupp gun and its 25-ton carriage from the Chesapeake Bay to Chicago.

The system of the use of mobile batteries on railways has been explained and advocated by the writer of this article in a work entitled Mobilizable Fortifications, published several years ago.

The guns of these batteries would have dispersed positions and converging fire, right and left, upon all points of the belts of land within their effective range, which ought not to be less than four miles; and, owing to the celerity of their motion, could be concentrated from points twenty or more miles distant before the columns of attack could march two miles within the zone of defensive fire.

The ordinary objection that railway cuts and surrounding hills would mask the batteries, and allow them to be approached and captured, or the rails to be torn up, is completely answered when it is considered that it is not one or two railway batteries that would be assailed, but continuous lines of batteries, having reasonable support, and beyond the ability of attack to outflank; so that when the front fire of a battery would be masked, the fire of batteries to the right and left would be encountered.

What number of railway batteries would be required to defend a hundred-mile section of railway, and how such batteries should be armed and how supported, are matters of military judgment and detail; but it is certain that, owing to their rapid mobility, a less number of guns and men would be needed than by the present system, while horses, field artillery, carriages, and caissons could be dispensed with, and probably not fifty batteries would be required, if suitably armed and endowed with motion.

Of course it would be simple folly to provide only a few railway batteries, for then they would not have mutual support, and could be flanked and the rails torn up; but if well equipped and in proper numbers, the links of the chain of defense would be complete, and an enemy would be compelled to make a front attack upon a line without flanks and growing stronger during the attack, owing to the mobility of the batteries, and to march three miles under artillery and machine-gun fire searching both of his flanks and his front, and increasing in intensity as he advanced, without support from his own artillery, as it is evident that none could be dragged into position by animals under the converging fire of the superior guns of the railway batteries.

The effectiveness of the defense of the batteries upon a line like this would be much improved by the use of electricity and of inflammable oils, particularly in localities presenting especial weakness or importance; but for want of space no details will be gone into, as the methods of use are very apparent.

Electric plants of sufficient power to destroy life might, in exceptional cases, be carried on rails, or even on land, while ordinarily the commercial plants of cities and villages within a radius of thirty miles could be utilized.

But when the use of these novel agencies is considered in relation to defense against naval attack, the application of electricity for that purpose presents doubts and difficulties that do not apply to the use of inflammable oils.

There is no doubt that there can be developed by suitable generators an electric current of sufficient power to destroy a ship of war, but the method of transmitting it so as to create actual contact, the mode of its operation and its effects, are matters of theory upon which no other data are available except those based upon deductions from the use of currents of inferior power.

There are many easy and practicable means of establishing actual contact with ships even when quite distant, and electricians can define the rate of power required to be destructive, and the devices to render it effective after contact be established; but it is manifest that a ship of war brought into actual contact with an electric current of 4000 volt power, or even less, would be in deadly peril, and the commercial electric plants of New York, Boston, and other cities might, at a minimum of cost, be utilized for experiment and service.

But the suggestion of the use of inflammable oils for defense against naval attack is one the practicability of which can be safely asserted, as the essential elements of it have passed beyond theory, and are in actual daily operation.

Let us consider, for example, a plan for the defense of the Mississippi River. The Ends jetties have for a considerable distance narrowed the width of the channel at its mouth to about four hundred feet, and inflammable oil, pumped or discharged from remote points, could easily be made available, even at the moment of attack, to sheet with oil the surface of the narrow channel, ready to be ignited when desirable, and to be carried forward by the current against any approaching hostile ship. From New Orleans to its mouth the river varies in width one thousand yards, more or less. At selected points remote from attack, when a hostile fleet would seek to ascend the river, from either bank could be discharged inflammable oil in ample quantity, ready, at the touch of an electric button, to burst into flames and be carried by the current against the enemy.

It would be impossible to ascend the river under these circumstances. What width of channel could be protected by fire defense cannot be stated with accuracy, as no exact data are available; but the capability of pumps is great and the oil supply ample, so that many points beside the Mississippi River could be barred by flames against ships. Most rivers could be, and also those ports where narrow and winding channels are the only means of entrance. Numerous ports and rivers, at home and abroad, could be indicated. The approaches to Constantinople and the Suez Canal might, amongst others, be barred by flames. It is probable that, at the trifling cost of a connection with the oil pipe lines, many of the channels leading into New York could be so barred, especially those entering by East River. There is now a width of only one thousand feet at low water from deep water below the Narrows to deep water beyond the Bars. The winding channels at Galveston and in Detroit River possibly could be thus defended, and many others beside.

A system of this kind would be more effective if carefully studied, prepared, and even experimented on in advance but it could be rapidly improvised, and even rubber pipes might be used in an emergency, and each fort, in the absence of pipe lines or other facilities, might be made a centre of oil distribution when necessary.

If a ship or fleet attempted to force a passage, and the conditions were such that a discharge of oil through pipes would not be effective, wooden hulks could be filled with oil, ready to become fire ships, scattering burning oil in every direction. They could be placed or towed in position by steam, cables, or other power, steered from land or otherwise, and fired and exploded when desired.

The possibilities of this system are very many and apparent. There are other devices and agencies that might be described, if space permitted.

These suggestions are made with no claim of originality, unless there be something of novelty in the proposal to combine them, after study and experiment, into a complete system.

When the vast extent of our coast lines, fronting upon the oceans, the Gulf, and the Great Lakes, is considered, the task of defending by permanent works only points of the first importance is almost too heavy to be borne, while even this cannot be accomplished in half a century; and therefore we should stimulate our studies to find something to be immediately available, and which, if shown by experiment to be effective and reliable, may afford security, and besides work enormous economy in money and time.

Our Great Lake cities are absolutely at the mercy of any one of the eighty gunboats, drawing less than ten or twelve feet of water, that England can introduce into the Lakes through the Canadian canals, and our government ought to find some speedy and effective method of protecting this defenseless wealth and population.

If by spending many millions we are able to protect New York and Brooklyn, what is to be done for the protection of the numerous cities, villages, and factories along Long Island Sound and the Massachusetts coast? How many forts, how many guns, will be required to protect even one half of them, and how much time and how many millions of taxes will be consumed before the thinnest shreds of defense can be created; and what of the rest of our coast, Lake, and Gulf lines?

Therefore, if it be possible to put heavy artillery upon rails, and move and fire it, as it is claimed that facts and experience have proved, would it not be well that the government should make some efforts to utilize this system for the defense of Long Island Sound, the Massachusetts coast, and other like localities? Ten heavy guns in permanent position would dominate only their limited fields of fire; but the same ten guns, if endowed with the rapid mobility which steam or other motors may give on rails, might defend almost every part of the mainland from New York to Point Judith, and perhaps beyond. Summoned by electricity when their presence might be required, and transported on rails, they could with great rapidity be moved twenty or thirty miles into prepared or open positions before the hostile ships could drop anchor, or even be near enough to fire a gun, and, in addition, could follow them to any menaced point.

The possibilities of commanding railways and a belt of land upon each side, by means of railway batteries of easy construction and little cost, should engage the attention of a practical and economical government like ours, with a small military establishment, exposed, as all governments are, to foreign and civil wars and broils; and the time may come when interests of immeasurable value may depend upon the government, with its small army, holding and protecting its great arterial food-bearing and coal-supplying railroads, which, if broken or seriously interrupted, would disorganize great centres of population, and paralyze military and commercial operations.

If it be practicable to do this, what folly not to do it! And how can the practicability be ascertained if the government fail to investigate and experiment? And there are the commercial railways, electric plants, and pipe lines ready, at a trifling cost of money, to furnish proof whether the achievements of peaceful industry can or cannot be successfully employed for its protection against the assaults of destructive war.

If by these means the superiority of defensive war over attack could be clearly established, there would follow a reduction of armaments, conscriptions, and war taxes. The certainty of defeat would restrain aggressive wars, and the energies of governments would be directed to improvement, and not to destruction.

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