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since a line of frontiers is chiefly intended to shut up the country which it covers.

3. When you are to construct a line of frontiers, you should avail yourself of all the obstacles which the ground that it traverses may offer: 4. That the line may have points of support, the open towns and villages enclosed by it should be fortified; this is particularly requisite when they occupy important points, and when, by their situation, they can see in reverse some other parts of

the line.

5. As all the points of a line of frontiers are not equally accessible to the enemy, the obstacles which form it do not all require the same degree of resistance; for instance, should some parts of the line traverse an open country, through which the enemy might easily penetrate, whilst others pass over a marshy or woody ground, &c., which scarcely allows him to approach, the former would undoubtedly require stronger defences than the

latter.

6. Since a line of frontiers is chiefly intended to secure the country behind it from the enemy's parties, the works which it contains do not require a greater relief than that which field-works commonly have; not even in its most accessible points; and, according to circumstances, from three to eight feet at most will suffice for the thickness of their parapets. It is scarcely necessary to observe, that the former dimension is applicable to such works as are only to be secured from the fire of musketry; and the latter to those which may be attacked with cannon.

7. Great advantages may be derived from streams, and particularly when they are broad and deep and have steep banks, or when the ground on their banks is marshy; should they contain islands, those on the side of the army must be occupied, in order to prevent the enemy from throwing up defences within them, under the protection of which he could more easily pass the stream; with regard to those on the the other side, they ought to be observed by posts which are ordered to retreat when the enemy appears with a superior force; all thickets, brushwood, &c., which might favor and conceal his movements, should be cut down. It is less important to occupy those islands than the others; besides, should they be attacked, you could not keep them on account of the impossibility of conveying a sufficient force to defend them.

8. All fords must be guarded by strong posts, and no bridges suffered to remain, except those which are indispensably necessary to penetrate into the enemy's country, should circumstances require it; when they are not situated within a fortress, or protected by it, the place where they stand should be more or less strongly fortified, according to the importance of the passage, and to the greater or less facility which the enemy may have of approaching them.

9. A small stream may also be rendered serviceable, by means of dams thrown across its bed; so as to form small inundations which render the access to the low parts of the ground more difficult to the enemy. The sluices of the water mills, manufactories, &c., which are commonly found on the banks of such streams, may be used likewise to that purpose, and those

Morasses too,

buildings should be fortified. and even marshes, are a very good barrier, as the enemy cannot attempt to pass them without danger, and particularly with his cannon; therefore, when the disposition and direction of the line allow some parts of it to be protected by such obstacles, you ought to avail yourself of them.

10. A few redoubts placed near the most accessible points of a ravine, and on those whence a reverse fire can be most easily obtained, will suffice to defend such passages.

11. The woods which are in the direction of the line, may also procure advantages by means of abatis made within them, and supported by a few detached works. The ground in front of the abatis should be cleared to a certain distance, in order that the enemy may not conceal his movements and approach unperceived.

12. Should a mountain be in the direction of the line, its passages must be guarded by posts sufficiently strong to secure them.

13. Wherever the country is open, and unprotected by natural obstacles, works ought to be thrown up, whose requisite strength depends on the importance of the points which they cover, the facility which the enemy may have of approaching them, and on the advantages which the ground affords for his manœuvres.

ii. Of Posts of Frontiers and other Posts.Posts of frontiers are intended to secure, with a limited number of troops, the principal points o a frontier which is not defended by an army, not by fortresses, the number, situation, and extent of which, are properly adapted to localities: for, should it be protected by such fortresses, their garrisons would suffice to guard it. It happens frequently that a frontier is actually defended by fortresses, but that they are not properly adapted to localities: in which case, intermediate points must be occupied by posts, so as to rectify the defects in the defence.

In a mountainous country, the valleys are chiefly inhabited, as they are more fertile and better supplied with water, communications and accommodations of all sorts, than the elevated parts; wherefore the towns, or villages situated within them, or near their openings, and in the plains contiguous to them, are particularly suitable to the establishment of posts: those which defend the principal gorges, and serve as places of rendezvous and depots, should be strongly fortified, and preceded by smaller posts, in order to watch the enemy's movements; with regard to the other gorges, they should be guarded by posts whose requisite strength depends on the facility which they may give to the enemy to penetrate into the country.

Flat and open countries are more difficult to guard than the preceding; a such countries, the chief towns should be occupied, and those placed on the communications be more or less strongly fortified, according to the importance of the points where they are situated; intrenched camps, of which we shall speak hereafter, may also be formed, where their position enables them to be of service for the general defence of the frontier. It is particularly requisite that those towns should be capable of a strong resistance, which

are situated in fertile plains, as armies attempt generally to advance through the most fruitful parts of a country.

No particular rule can be given, with regard to the method of fortifying posts of frontiers, since it depends on the configuration of the ground, the time which you can command, &c. But, as those posts are intended to serve instead of fortresses, particular attention must be paid to the dispositions for their defence; and that you should avail yourself of every advantage which localities may offer; a stream which allows an inundation to be formed, or whose passage may be rendered difficult to the enemy by other convenient means, an impassible morass which secures part of the post, or a marshy ground which obstructs the approach to it; a wood where an abatis, properly supported, can he made; or which must be entirely cut down, as it would conceal the enemy's movements, and expose the post to be surprised; buildings, which, being placed between two works, form a sort of curtain connecting their defences, and whose walls may be pierced with loop-holes; or which project in front of the post, and will flank part of it, after being secured by works, or by other practicable dispositions: some other buildings which must be pulled down, either because they would mask the fire of the post and render it less effective, or because they would favor the enemy's approach, and enable him to see into the post; a street, which should be barricaded, or cut across by trenches: some particular points, where works must be thrown up, as, on account of their situations, their fire will flank other works, or defend them in reverse: a ravine, a ditch, a steep ground, &c., which may strengthen the defence, or which would weaken it, should not proper precautions be taken: these, and other considerations, which circumstances may require, should fix the attention of an engineer, in forming his plan for the defence of a post, and, if he cannot depend upon sufficient time to complete all the dispositions which are requisite, he must attend, first, to the most essential; next, to those which are less important; and ultimately to the formation of such works and obstacles as will improve the defence of the post, although it may not indispensably require them. The first step to be taken, in such a case, is to secure the post from a coup de main. It is scarcely necessary to observe, that the defences thrown up for that purpose must be so disposed as not to prevent the addition of others, should circumstances permit it.

Let us suppose that an army intends to invade the territory of the enemy, and to remain therein; in this case, the march of the army requires particular precautions suitable to the nature of the frontier through which it proposes to penetrate: for instance, should the frontier be protected by fortresses well calculated in all respects for its defence, they must be taken as the army advances, and then be repaired, garrisoned, and supplied with stores and provisions, in order to keep in awe the invaded country, and afford points of support which may secure the army's retreat, should it be compelled to fall back, and supply all its wants; but if the country is open,

and destitute of fortresses, posts strongly fortified must be established near the principal communications, and in the points most advantageously situated to defend it, and secure the army's retreat, if necessary; indeed, less precautions are requisite, when the army which invades such a country intends only to make a temporary stand, either to levy contributions, or to draw in the eneiny and make a diversion; however, it should occupy, as it advances, the principal communica tions, and the positions which will secure its flanks and rear; as, otherwise, its subsistencies would be continually exposed to be burnt or taken away by the parties of the enemy; besides the rear of the army would be annoyed, and the army, perhaps, be cut off.

The winter quarters of an army, and particularly in a hostile country, should also be covered by posts so placed as to defend the principal communications; for without it the quarters will not be secure, nor will the troops enjoy any repose, as they may be attacked at every moment: nay, should the enemy take the field early, and attack the quarters before they have time to assemble, he might crush them, and thus destroy part of the army in the beginning of the campaign.

As all posts should be fortified according to the same general principles, we refer the reader to the hints which we have given, when speaking of posts of frontiers.

iii. Of intrenched Camps of Frontiers.-Some of the positions to be occupied along a frontier, for its defence, may not be inhabited, or the number of habitations which they contain may be too small for the troops, which in those two cases must be encamped; and then the positions take the name of intrenched camps of frontiers.

There are two sorts of intrenched camps of frontiers; namely, those which have a small extent, and are only intended to guard the points where they are placed; they differ from posts of frontiers, of which we have been speaking in the preceding section, merely because they are situated in an uninhabited place; and what we have explained, with regard to the former, is also applicable to the latter, with some modifications which the difference in their situation may require. The other intrenched camps of frontiers contain a considerable body of troops, and are intended not only to guard the points where they are established, but to cover the country; these camps, which are formed for the same purpose as flying camps, and only differ from them as they are fortified, afford great advantages, when properly disposed; they keep the enemy in check, and prevent him from penetrating through some weak points of the frontier, in order to advance in the country; for then his flanks and rear would be exposed to be attacked by the en camped troops, as they can march in all direc tions; his lines of communication would not b safe, and his retreat might be cut off. It is evi. dent that camps of this sort require to be so for tified as to afford a resistance proportionate to their object, and to the importance of the points which they occupy; and that their situations must be such as not to expose them to be rapidly and unexpectedly surrounded; for the troops

could not march to the tareatened points, nor make good their retreat when their safety required it; and therefore they would be exposed to no purpose.

The proper situation for an intrenched camp of frontiers requires, likewise, that it cannot be taken in reverse, nor the troops prevented from retreating or communicating with other parts of the frontier, according to circ imstances; and that the enemy may not, by crushing some posts, oblige the encamped troops to withdraw from their intrenched position, for fear of their retreat being cut off. Lastly, it should be examined, whether the situation of the camp affords easy means to penetrate into the enemy's country, should such offensive movement le requisite, and whether it can be placed in spot protected by some natural obstacles, as ther it will require less time and labor in fortifying.

iv. Of grand tétes de pont.-When part of a frontier is covered by a river, it is necessary to secure the principal communications across it, so that an army may march to the enemy's country, or retreat from it, according to circumstances: grand têtes de pont are constructed for that purpose.

It is evident that grand têtes de pont ought to be capable of a great resistance; for, as their object is very important, the enemy has a material interest in destroying them; they require also a rather considerable extent, in order to contain a sufficient number of troops to check him, when the army is advancing or retreating through them. Lastly, they must be so disposed as to prevent him from perceiving the bridges which they encompass; otherwise he would attempt to destroy them from a distance, with his

cannon.

When the communication to be secured is situated in a town, and not seen from without, the part of the town beyond the river must be fortified, and then it serves as a tête de pont.

But should the opening of the communication be outside of the town, and seen from the country, not only the town must be fortified, but the opening requires to be covered by works sufficiently extensive to hide the bridges; or the points from which the enemy can see and batter them must be fortified.

Lastly, if the communication is at a certain distance from the town, its opening towards the enemy should be fortified, and the requisite precautions taken to secure the bridges from being battered.

It happens frequently that these grand communications across rivers are only established in time of war; wherefore, the bridges which form them have no great solidity: in this case, stoccados should be constructed in the upper part of the river, so as to stop every thing which the enemy may let go with the current, to break open or destroy the bridges. When there are islands near a tête de pont, those whence the enemy could take it in reverse or batter the bridges should be fortified.

A single house, when it has no stone walls, may be fortified in the following manner: the walls may be strengthened by boards in the inside, or by rafters applied as in blockhouses, or,

if these are wanting, by making a ditch round it, and using the earth to strengthen the wall. The doors and windows are fortified with boards, and barricadoed. Loop-holes are every where made, but in such a direction that the enemy cannot reach them with his firelocks, so as to fire into the inside of the house. If there is no ditch round it, other impediments are to be made use of, to hinder the enemy from approaching close to the wall. The roof is broken down, and all combustible matter covered with earth and rubbish, to defend the house from an attack from above, which might otherwise be executed by ladders. In a stone house, the walls will generally be strong enough, or, if not, they are to be prepared as above. The same is also to be observed respecting the windows and the roof; and, if possible, it is to be made shell proof from above. The doors are either barricadoed, or defended by a tambour constructed before them, to have a flanking fire.

A church-yard, a farm, or an estate, is fortified in a similar manner; but, if surrounded by a wall, either loop-holes are made through it, or, if too high, a kind of scaffolds, called echafaudages, are to be erected, serving for the soldiers to stand upon while firing. The church, or the building on an estate, are then generally used as a corps de garde, and made shell proof, by breaking down the roof and the uppermost story, and using it to cover the building. The doors, and particularly the corners of the walls round such a place, are generally covered by tambours; but, if time permits, caponniers, and other impediments to the advancing of the enemy, are made use of. The street and roads, leading towards them, are generally made impracticable by old or broken carts, harrows, boards with nails, wheels, &c. All the houses in the neighbourhood, which may be advantageous for the enemy, or which may favor or cover his approach, are levelled, and the rubbish of them used to strengthen the walls. The trees near such a place, if large, are hewed down or sawed off, that even not a single rifleman may approach covered by any of these parts.

A small, or country town, if surrounded by a wall, is fortified in a similar manner; but echafaudages are generally used behind its walls, and, if possible, two rows of soldiers are employed, one firing through loop-holes, and the other over the walls. Guns are placed wherever their fire is of the best effect. The gates are barricadoed, and covered by impediments which hinder the enemy from advancing; besides this, they are covered by traverses, and a flanking fire is established before them, if possible. Only such parts of the gates as are essentially necessary to be open for the communication are not barricadoed, but strongly defended, while every thing is to be done that may render the interior communication better and more easy, by means of sufficien passages.

PART III.

ON THE ATTACK OF FORTIFIED PLACES. It has been suggested that our treatise on the above art requires some detailed mode of attack, as one of the best exemplifications of the doc

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