Part 42

Some authors think these works never answer the expence; however, M. Vauban was so sensible of their utility, that he never failed to make them when the ground was convenient for it; because, when such works are defended by a skilful governor, they will afford the means of being valiantly supported.

_Gorge_, of a bastion, is the interval between the extremity of one flank and that of the other.

_Gorge_, of any work, is that part next to the body of the place, where there is no rampart or parapet; that is, at the counterscarp of the ditch.

_Half-moon._ (_Fr._ _Demi-Lune_.) Is an out-work that has two faces which form a saliant angle, the gorge of which resembles a crescent. It owes its original invention to the Dutch, who use it to cover the points of their bastions. This kind of fortification, is, however, defective, because it is weak on its flanks. Half-moons are now called ravelins; which species of work is constructed in front of the curtain. See RAVELINS.

_Gorge of a half moon_, the distance between the two flanks, taken on the right of the counterscarp.

_Head of a work_, its front next the enemy, and farthest from the place.

_Horn-work_, is composed of a front and 2 branches: the front is made into 2 half bastions and a curtain: this work is of the nature of a crown-work, only smaller, and serves for the same purposes. The use of horn-works in general is to take possession of some rising ground advanced from the fortification; the distance of which determine that of the horn-work; and they are placed either before the curtain, or before the bastions, according to circumstances.

_Horse-shoe_, is a small round or oval work, with a parapet, generally made in a ditch, or in a marsh.

_Insult._ A work is said to be _insulted_, when it is attacked suddenly and openly.

_Interior side of a fortification_, an imaginary line drawn from the centre of one bastion to that of the next, or rather the curtain produced till they meet.

_Lodgment_, See SIEGE.

_Loop-holes_, are either square, or oblong holes, made in the wall, to fire through with musquets. They are generally 8 or 9 inches long, 6 or 7 inches wide within, and 2 or 3 feet without; so that every man may fire from them direct in front, or oblique to right or left, according to circumstances.

_Lunettes_ in fortification, are works made on both sides of a ravelin: one of their faces is perpendicular to half or ²⁄₃ds of the faces of the ravelin, and the other nearly so to those of the bastion.

There are likewise lunettes, whose faces are drawn perpendicular to those of the ravelin, within ¹⁄₃ part from the saliant angle; whose semi-gorges are only 20 fathoms.

These kind of works make a good defence, and are of no great expence; for as they are so near the ravelin, the communication with it is very easy, and one cannot well be maintained till they are all three taken.

_Lunettes_, are also works made beyond the second ditch, opposite to the places of arms: they differ from the ravelins only in their situation.

_Lunettons_, are small lunettes.

_Merlon_, is that part of the breast-work of a battery which is between the embrasures.

_Orillon_, is a part of the bastion near the shoulder, which serves to cover the retired flank from being seen obliquely: it is sometimes faced with stone, on the shoulder of a casemated bastion, to cover the cannon of the retired flank, and hinder them from being dismounted by the enemy’s cannon.

Of all the works in a fortification, there is none more capable of defending the passage of the ditch, and to destroy the miner, wheresoever he enters himself, than the orillon. Experience in the last war has shewn us of what vast advantage it is to have 2 or 3 reserve pieces of cannon, which command the ditch, and the face of the opposite bastion, in such a manner as to destroy the attempts of the miners, and see the breach in reverse. Hence the great advantages of a double flank thus concealed weigh so very much with us, and convince us so entirely of their usefulness, that we affirm no place to be well fortified without the orillon, and that the straight flank is fit for nothing but field works.

The orillon is as old as the bastion, and was first made use of about the year 1480; and we find it frequently mentioned in the works of Pasino and Speckle, first published in 1579.

_Out-works._ See WORKS.

_Palisades_, in fortification, are a kind of stakes made of strong spars about 9 feet long, fixed 3 deep in the ground, in rows about 6 inches asunder: they are placed in the covert-way, at 3 feet from, and parallel to the parapet of the glacis, to secure it from being surprised.

_Parapet_, in fortification, is a part of the rampart of a work, 18 to 20 feet broad, and raised 6 or 7 feet above the rest of the rampart: it serves to cover the troops placed there to defend the work against the fire of the enemy.

_Parallels._ See SIEGE.

_Port-cullice_, in fortification, is a falling gate or door, like a harrow, hung over the gates of fortified places, and let down to keep out the enemy.

_Place_ is the term commonly used in fortification instead of a fortified town.

_Regular place_, one whose angles, sides, bastion, and other parts are equal, &c.

_Irregular place_, one whose sides and angles are unequal, &c.

_Place of arms_, in fortification, is a part of the covert-way, opposite to the re-entering angle of the counterscarp, projecting outward in an angle. It is generally 20 fathoms from the re-entering angle of the ditch on both sides, and the faces are found by describing a radius of 25 fathoms.

_Places of arms._ See SIEGE.

_Pits_, or _ponds_, in fortification, are little holes dug between the higher and lower curtains, to hold water, in order to prevent the passing from the tenailles to the flanks.

_Profiles_, in fortification, are a representation of the vertical sections of a work; and serve to shew those dimensions which cannot be described in plans, and are yet necessary in the building of a fortification; they may be very well executed and constructed upon a scale of 30 feet to an inch. By a profile are expressed the several heights, widths, and thicknesses, such as they would appear were the works cut down perpendicularly from the top to the bottom. See PROFILES.

_Rampart_, is an elevation of earth raised along the faces of any work, 10 or 15 feet high, to cover the inner part of that work against the fire of an enemy: its breadth differs according to the several systems upon which it may be constructed: for De Ville makes them 12¹⁄₂ fathoms, M. Vauban 6, and others 10 fathoms.

_Rams-horns_, in fortification, are a kind of low work made in the ditch, of a circular arc; they were first invented by Mr. Belidor, and serve instead of tenailles.

_Ravelin_, in fortification, is a work placed before the curtain to cover it, and prevent the flanks from being discovered sideways, it consists of 2 faces meeting in an outward angle. Some ravelins are counter-guarded, which renders them as serviceable as either the cunettes, or tenaillons.

_Gorge of the ravelin_, is the distance between the two sides or faces towards the place.

_Gorges_, of all other outworks, are the intervals or spaces which lie between their several wings or sides towards the main ditch. See GORGES.

_Redans_, in fortification, are a sort of indented works, consisting of lines or facings that form sallying or re-entering angles, flanking one another, and are generally used on the sides of a river running through a garrisoned town. They were used before bastions. Sometimes the parapet of the covert-way is carried on in this manner.

_Redoubt_, is a kind of work placed beyond the glacis, and is of various forms. Its parapet, not being intended to resist cannon, is only 8 or 9 feet thick, with 2 or 3 banquettes. The length of the sides may be from 10 to 20 fathoms.

_Redoubt_, is also the name of a small work, made sometimes in a bastion, and sometimes in a ravelin, of the same form.

_Redoubt_, is likewise a square work without any bastions, placed at some distance from a fortification, to guard a pass or to prevent an enemy from approaching that way.

_Detached-redoubt_, is a kind of work much like a ravelin, with flanks placed beyond the glacis: it is made to occupy some spot of ground which might be advantageous to the besiegers; likewise to oblige the enemy to open their trenches farther off than they would otherwise do. Their distance from the covert-way should not exceed 120 toises, that it may be defended by musquet shot from thence.

_Redouts-en-cremaillere_, so called from their similitude to a saw; the inside line of the parapet being broken in such a manner, as to resemble the teeth of a saw; whereby this advantage is gained, that a greater fire can be brought to bear upon the defile, than if only a simple face was opposed to it, and consequently the passage is rendered more difficult.

_Retrenchment_, in fortification, is any work raised to cover a post, and fortify it against an enemy, such as fascines loaded with earth, gabions, sand-bags, &c.

_Revetement_, in fortification, is a strong wall built on the outside of the rampart and parapet, to support the earth, and prevent its rolling into the ditch. When the revetement of a rampart goes quite up to the top, 4 feet of the upper part is a vertical wall of 3 feet thick, with a square stone at the top of it, projecting about 5 or 6 inches, and a circular one below, or where the slope begins, of 8 or 10 inches diameter. They go quite round the rampart, and the circular projection is called the _cordon_.

_Rideau_, in fortification, is a small elevation of earth, extending lengthways on a plane, and serving to cover a camp, or to give an advantage to a post. They are also convenient for the besiegers of a place, as they serve to secure the workmen in their approaches to the foot of a fortress.

_Rideau_ is also used sometimes for a trench, the earth of which is thrown up on its sides, to serve as a parapet for covering the men.

_Sap._ See SIEGE.

_Scarp_, is, properly speaking, any thing high and steep, and is used in _fortification_ to express the outside of the rampart of any work next to the ditch.

_Sillon_, in fortification, a work raised in the middle of a ditch to defend it when too broad. This work has no particular construction, but as it runs, forms little bastions, half moons, and redans, which are lower than the rampart of the place, but higher than the covert way. It is not much used at present.

_Sillon_ means literally a furrow. In fortification, it is a work raised.

_Swallow’s-tail_, a kind of out-work, only differing from a single tenaille, in that its sides are not parallel as those of the tenaille, but narrower towards the town than towards the country.

_Talus_ signifies a slope made either on the outside or inside of any work, to prevent the earth’s rolling down; it is of various denominations, viz.

_Talus of the banquette_ is that gentle slope from the top of the banquette to the horizontal line.

_Interior talus of the parapet_, the slope from the top of the parapet to the banquette.

_Talus of the top of the parapet_, that slope which lessens the height of the parapet towards the berm, by which means the troops firing from the banquette can defend the covert way.

_Exterior talus of the parapet_, the slope of the parapet from the top to the berm.

_Interior talus of the ditch_, the slope from the top of the ditch to the bottom, within.

_Tenailles_ are low works made in the ditch before the curtains; of which there are three sorts. The first are the faces of the bastion produced till they meet, but much lower; the second have faces, flanks, and a curtain; and the third have only faces and flanks. Their height is about 2 or 3 feet higher than the level ground of the ravelin. Their use is to defend the bottom of the ditch by a grazing fire, as likewise the level ground of the ravelin, and especially the ditch before the redoubt within the ravelin, which cannot be defended from any other quarter so well as from them.

_Tenaillons_ are works made on each side of the ravelin, much like the lunettes; with this difference, that one of the faces in a tenaillon is in the direction of the ravelin; whereas that of the lunette is perpendicular to it.

_Terre-pleine_, in fortification, the horizontal superficies of the rampart, between the interior talus and the banquette. It is on the _terre pleine_ that the garrison pass and repass; it is also the passage of the rounds.

_Tower bastions_ are small towers made in the form of bastions; first invented by M. Vauban, and used in his second and third method; with rooms or cellars underneath, to place men and artillery in them. As these towers are almost a solid piece of masonry, they must be attended with great expence, though their resistance can be but little; for it has been found by experience, that the casemates are but of little use, because as soon as they have fired once or twice, the smoke will oblige the defenders to leave them, notwithstanding the smoke holes: hence it may be concluded, that the strength of these tower bastions does by no means answer their expences; and that, if small bastions were made instead of them, without casemates, they would be much better, and less expensive.

_Traditore_, in fortification, signifies the concealed or hidden guns in a fortification, behind the reverse of the orillon.

_Traverse_, in fortification, is a parapet made across the covert way, opposite to the saliant angles of the works, and near the places of arms, to prevent enfilades; they are 18 or 20 feet thick, and as high as the ridge of the glacis. There are also traverses made in the caponniers, but then they are called _tambours_.

_Traverses_ are likewise made within other works, when there are any hills or rising grounds from whence the interior parts of these works may be observed. Traverses that are made to cover the entrances of redoubts in the field, need not be above 8 or 10 feet thick.

_Trous-de-loup_, or wolf holes, round holes made about 5 or 6 feet deep, with a stake in the middle: they are generally dug round a field redoubt, to obstruct the enemy’s approach; circular at top, and about 4¹⁄₂ feet diameter; pointed at the bottom like an inverted cone. Two or three rows of them are dug chequerwise, about 6 paces from the edge of the ditch, viz. two rows of holes exactly opposite to each other, and a third row in the middle, covering the intervals.

_Wicket_, a small door in the gate of a fortified place, at which a man on foot may go in, and which may be opened though the gate itself be kept shut.

_Works._ All the fortifications about a place, are called the _works_ of a place.

_Out-works._ All detached _works_ in a fortification are so called. See _Dehors_.

_Zig-Zag._ See SIEGE.

_The principal maxims of fortification_, are these, viz. 1. That every part of the works be seen and defended by other parts, so that an enemy cannot lodge any where without being exposed to the fire of the place.

2. A fortress should command all places round it: and therefore all the out works should be lower than the body of the place.

3. The works farthest from the centre should always be open to those that are nearer.

4. The defence of every part should always be within the reach of musquet shot, that is, from 120 to 150 fathoms, so as to be defended both by ordnance and small fire arms; for if it be only defended by cannon, the enemy may dismount them by the superiority of their’s, and then the defence will be destroyed at once; whereas, if a work is likewise defended by small arms, if the one be destroyed, the other will still subsist.

5. All the defences should be as nearly direct as possible; for it has been found by experience, that the soldiers are too apt to fire directly before them, without troubling themselves whether they do execution or not.

6. A fortification should be equally strong on all sides; otherwise the enemy will attack it in the weakest part, whereby its strength will become useless.

7. The more acute the angle at the centre is, the stronger will be the place.

8. In great places, dry ditches are preferable to those filled with water, because sallies, retreats, succors, &c. are necessary; but, in small fortresses, wet ditches, that can be drained, are the best, as standing in need of no sallies.

_Field_ FORTIFICATION is the art of constructing all kinds of temporary works in the field, such as redoubts, field forts, star forts, triangular and square forts, heads of bridges, and various sorts of lines, &c. An army intrenched, or fortified in the field, produces, in many respects, the same effect as a fortress; for it covers a country, supplies the want of numbers, stops a superior enemy, or at least obliges him to engage at a disadvantage.

The knowlege of a field engineer being founded on the principles of _fortification_, it must be allowed, that the art of fortifying is as necessary to an army in the field, as in fortified places; and though the maxims are nearly the same in both, yet the manner of applying and executing them with judgment, is very different.

A project of fortification is commonly the result of much reflexion; but in the field it is quite otherwise: no regard is to be had to the solidity of the works; every thing must be determined on the spot; the works are to be traced out directly, and regulated by the time and number of workmen, depending on no other materials than what are at hand, and having no other tools than the spade, shovel, pick-axe, and hatchet. It is therefore in the field, more than any where else that an engineer should be ready, and know how to seize all advantages at first sight, to be fertile in expedients, inexhaustible in inventions and indefatigably active.

_Quantity and quality of the materials which are required in the construction of field-fortification._

1. Every common fascine made use of in the construction of field works or fortifications, should be 10 feet long and 1 foot thick. A fascine is raised by means of 6 pickets, which are driven obliquely into the earth, so that 2 together form the shape of a cross. These pickets are tied with willows, or birch twigs. It is upon supporters or tressels of this kind, that fascines are made, which are properly fagots bound together with rods, at intervals of 1 foot each in breadth. Six men are required to complete each fascine; viz. 2 to cut the branches, 2 to gather them up, and 2 to bind the fascines. Six men may with great ease, make 12 fascines in an hour. The smaller sort of willows, or birch twigs, are best calculated for this work. The fascines are fastened to the parapet, which would otherwise crumble and fall down. A redoubt, constructed _en crémaillere_, must have fascines 8 feet long.

2. There must be 5 pickets for each fascine, and each picket must be 3 or 4 feet long, an inch and a half thick, and sharp at one end; they serve to fasten the fascines to the parapet.

3. When you cannot procure wood for the fascines, the parapet must be covered or clothed with pieces of turf, 4 inches thick, and a foot and a half square; these are fastened to the parapet with 4 small pickets 8 inches long.

4. The fraises, or pointed stakes, must be 8 feet long, 5 inches thick, and be sharp at the top. The beams upon which they are laid, must be 12 feet long and 6 inches thick. These beams are spread horizontally along the parapet, and fraises are fixed to them, with nails 7 inches long; after which the beams are covered with earth. Two men will make 12 fraises in an hour.

5. The palisades, by which the ditch or fossé of a work is fortified, must be 9 or 10 feet long, and 6 inches thick; they must, likewise, be sharpened at the end. If you cannot procure them of these dimensions, you must use smaller ones; in which case you will have the precaution to mix a few large stakes.

6. The pickets, which are fixed in _trous-de-loup_ or wolf-holes, must be 6 feet long, 4 inches thick, and sharp at the top.

7. The beams belonging to a _cheval-de-frize_ must be 12 feet long, and 6 inches broad. The spokes which are laid across, must be 7 feet long, 4 inches thick, and placed at the distance of 6 inches from each other. These _chevaux-de-frizes_ are made use of to block up the entrances into redoubts, to close passages or gates, and sometimes they serve to obstruct the fossé.

8. Gabions are constructed of various sizes. Those which are intended for field works, must be 3 or 4 feet high, and contain 2 or 3 feet in diameter. These gabions are made by means of long stakes, 3 or 4 feet long, which are placed so as to form a circle, which is 2 or 3 feet in diameter. The pickets must be covered and bound in the same manner as hurdles are. Gabions are chiefly of use in embrasures. They are fixed close to each other, and are afterwards filled with earth. There are also gabions of one foot, with 12 inches diameter at the top, and 9 at the bottom. The bank of the parapet is lined with gabions of this construction, behind which troops may be stationed, so as to fire under cover through the intervals. A quantity of large wooden mallets, rammers, hatchets, axes, and grappling irons, is required for this work.

_Names of all works used in field_ FORTIFICATION.

_Bridge heads_, or _têtes de pont_, are made of various figures and sizes, sometimes like a redan or ravelin, with or without flanks, sometimes like a horn or crown work, according to the situation of the ground, or to the importance of its defence. Their construction depends on various circumstances; for, should the river be so narrow, that the work may be flanked from the other side, a single redan is sufficient; but when the river is so broad, that the saliant angle cannot be well defended across the river, flanks must be added to the redan; but should a river be 100 toises, or more across, half a square may be made, whose diagonal is the river side; and where the river is from 3 to 500 toises broad, a horn, or crown-work should be made. All the different sorts of _heads of bridges_, are to be esteemed as good works against a sudden onset only, and their use is almost momentary, as they sometimes serve but for a few days only, and at most during a campaign.

_Dams_ are generally made of earth, but sometimes of other materials, as occasion may require: their use is to confine water.

_Flêche_ a work consisting of two faces, terminating in a saliant angle of 90°, the faces are generally 75, or 80 feet long, the parapet 6 feet thick, and the ditch 7 feet broad.

_Forts_, in field fortification, are of various sorts, viz.

_Field forts_ may be divided into two kinds: the one defending itself on all sides, as being entirely surrounded; the other, bordering on a river, &c. remain open at the gorge. They have the advantage of redoubts, in being flanked, and the disadvantage in containing less within, in proportion to their extent.

_Star forts_ are so called, because they resemble that figure. They were commonly made of 4 angles, sometimes of 5, and very rarely of 6; but we find them now made of 7 and 8 angles. Let their figure however, be what it will, their angles should be equal; if formed of equilateral triangles, so much the better; for then the flanking angle being 120°, the fires cross better and nearer; and as the 2 flanks are on the same line, the space not defended before the saliant angle, is reduced to a parallelogram, whose smallest side is equal to the gorge.

_Bastioned forts_ differ in nothing from that of places, except that the figure is less, and the attack supposed of another kind. It is reckoned sufficient to flank them with half bastions.

_Triangular forts._ As these kind of _forts_ contain less in proportion than any other, they are consequently used as seldom as possible.

_Square forts_ are in many respects preferable to the triangular ones. See FORT.