The ramparts and parapets of these sorts of works are commonly made of turf, and the outside of the parapet is fraised; that is, a row of pallisades are placed about the middle of the slope, in an horizontal manner, the points declining rather a little downwards, that the grenades or fireworks thrown upon them may roll down into the ditch; and if the ditch is dry, a row of pallisades should be placed in the middle of it, to prevent the enemy from passing over it unperceived, and to secure the fort from any surprise.
Fortde campagne,Fr.a field fortification, SeeFortification.
FORTERESSE,Fr.Fortress. Any strong place rendered so by art, or originally so by local advantages, or by means of both nature and art. Places which are strong by nature generally stand upon mountains, precipices, in the middle of a marsh, on the sea-coast, in a lake, or on the banks of some large river. Places which are strong by art, owe their strength to the labor of man, whose ingenuity and perseverance substitute ditches and ramparts where mountains and rivers are wanting.
FORTIFICATION, is the art of fortifying a town, or other place; or of putting it in such a posture of defence, that every one of its parts defends, and is defended by some other parts, by means of ramparts, parapets, ditches, and other outworks; to the end that a small number of men within may be able to defend themselves for a considerable time against the assaults of a numerous army without; so that the enemy, in attacking them, must of necessity suffer great loss.
Fortificationmay be divided into ancient and modern; offensive, and defensive; regular, and irregular; natural, and artificial, &c.
AncientFortification, at first, consisted of walls or defences made of trunks, and other branches of trees, mixed with earth, for security against the attacks of an enemy. Invention owes its origin to necessity;fortificationseems to have had fear for its basis; for when man had no other enemy but the wild beasts, the walls of his cottage were his security; but when pride, ambition, and avarice, had possessed the minds of the strong and the daring to commit violences upon their weaker neighbors, either to subject them to new laws, or to plunder their little inheritance, it was natural for the latter to contrive how to defend themselves from such injuries.
Our Aborigines of North America, have left traces offortificationin its infancy, of which there are some curious and magnificent remains on theMiamiriver, in the state of Ohio.
There are abundance of Indian villages fenced round by long stakes driven into the ground, with moss or earth to fill the intervals; and this is their security (together with their own vigilance) against the cruelty of the savage neighboring nations.
Nor isfortificationmuch less ancient than mankind; for Cain, the son of Adam, built a city with a wall round it upon mount Liban, and called it after the name of his son Enoch, the ruins of which, it is said, are to be seen to this day; and the Babylonians, soon after the deluge, built cities and encompassed them with strong walls.
At first people thought themselves safe enough with a single wall, behind which they made use of their darts and arrows with safety: but as other warlike instruments were continually invented to destroy these feeble structures, so on the other hand persons acting on the defensive were obliged to build stronger and stronger to resist the new contrived forces of the desperate assailants.
What improvements they made in strengthening their walls many ages ago, appear from history. The first walls we ever read of, and which were built by Cain, were of brick; and the ancient Grecians, long before Rome was ever thought of, used brick and rubble stone, with which they built a vast wall, joining mount Hymetus to the city of Athens. The Babylonian walls, built by Semiramis, or, as others will have it, by Belus, were 32 feet thick, and 100 feet high, with towers 10 feet higher, built upon them, cemented with bitumen or asphaltus. Those of Jerusalem seem to have come but little short of them, since, in the siege by Titus, all the Roman battering rams, joined with Roman art and courage, could remove but 4 stones out of the tower of Antonia in a whole night’s assault.
Afterfortificationhad arrived at this height it stopped for many ages, ’till the use of gunpowder and guns was found out; and then the round and square towers, which were very good flanks against bows and arrows, became but indifferent ones against the violence of cannon; nor did the battlements any longer offer a hiding place, when the force of one shot both overset the battlement, and destroyed those who sought security from it.
ModernFortification, is the way of defence now used, turning the walls into ramparts, and square and round towers into bastions, defended by numerous outworks; all which are made so solid, that they cannot be beat down, but by the continual fire of several batteries of cannon. These bastions at first were but small, their gorges narrow, their flanks and faces short, and at a great distance from each other, as are those now to be seen in the city of Antwerp, built in 1540 by Charles V. emperor of Germany; since which time they have been greatly improved and enlarged, and are now arrived to that degree of strength, that it is almost a received opinion, that the art of fortification is at its height, and almost incapable of being carried to a much greater perfection.
OffensiveFortification, shews how to besiege and take a fortified place; it further teaches a general how to take all advantages for his troops; the manner of encamping, and method of carrying on either a regular or irregular siege, according as circumstances may direct.
DefensiveFortification, shews a governor how to make the most of a garrison committed to his care, and to provide all things necessary for its defence.
RegularFortification, is that built in a regular polygon, the sides and angles of which are all equal, being commonly a musquet shot from each other, and fortified according to the rules of art.
IrregularFortification, on the contrary, is that where the sides and angles are not uniform, equi-distant, or equal; which is owing to the irregularity of the ground, vallies, rivers, hills, and the like.
ToFortifyinwards, is to represent the bastion within the polygon proposed to be fortified; and then that polygon is called theexterior polygon, and each of its sides theexterior side, terminating at the points of the two nearest bastions.
ToFortifyoutwards, is to represent the bastion without the polygon proposed to be fortified, and then the polygon is called theinterior polygon, and each of its sides theinterior side, terminating in the centres of the two nearest bastions.
ElementaryFortification, by some likewise called the theory of fortification, consists in tracing the plans and profiles of a fortification on paper, with scales and compasses; and examining the systems proposed by different authors, in order to discover their advantages and disadvantages. The elementary part is likewise divided intoregularandirregular fortification, which see.
FrontFortification, any proportion of the body of a place, consisting of two half bastions and a curtain.
PracticalFortification, consists in forming a project of a fortification, according to the nature of the ground, and other necessary circumstances, to trace it on the ground, and to execute the project, together with all the military buildings, such as magazines, store houses, barracks, bridges, &c.
The names of every part of aFortification; and first of lines, which are divided into right lines, and curve lines.
Line of defence, is the distance between the saliant angle of the bastion, and the opposite flank; that is, it is the face produced to the flank. Common experience, together with some of the greatest artists in fortification, unanimously agree, that thelines of defencemay extend (though not exceed) 150 fathom. Some indeed will affirm, that as a musquet does not carry more than 130 fathom point blank, the angle of the bastion should be no further removed from its opposite flank. We agree that a musquet carries no farther point blank; but we are sure it will do execution, and kill, at 180 fathom. The enemy generally makes his breaches near the middle of the face; which if granted, the line of fire from the flank to the breach, scarcely exceeds 130 fathom; besides, the cannon of the flank does less execution upon a shortline of defencethan on a long one.
Line of defence fichant, is a line drawn from the angle of the curtain, to the point of the opposite bastion, which is not to exceed 120 fathom; and from the point of the curtain, and flank, to the face of the opposite bastion, which is to be defended. This line may not improperly be called in good English thebutting flank, since it partly sees the opposite faces in reverse; and the shot from it, especially near the orillon, strike against the faces. Authors are numerous both for and against thefichantandrasantlines; we can only set down as a fixed rule, that the more powerful the active quality is, the more the passive must suffer; that in fortification the active quality is the fire, which discovers the assailants (who are the passive) going to attack the face of the opposite bastion; consequently, the more this active quality is augmented, by so much the more must the passive subjects suffer; and from thence we argue for thefichant flank, since it augments this active quality, by all the fire of the curtain added to the flank, which is the principal action in the art of defence.
Line of defence rasant, is a line drawn from the point of the bastion along the face, ’till it comes to the curtain, which shews how much of the curtain will clear, or defend the face. This line may very justly in our language be called thesweeping flank; because the shot as it were sweeps along the opposite faces. This line, as well as thefichant, has many supporters, and as many opponents. In our humble opinion, theline fichantis preferable to theline rasant.
Line of circumvallation.SeeSiege. SeeCircumvallation.
Line of contravallation.SeeContravallation.
Line of counter-approach.SeeApproaches.
Capital line, is an imaginary line which divides the work into two equal and similar parts, or a line drawn from the point of the bastion to the point where the two demi-gorges meet, &c.
Line of defence prolonged. In the square, and most polygons of the lesser fortification, you prolong the line of defence; but in the polygons of the greater and meaner, you draw a line from the angle of the opposite shoulder to the angle of the curtain, upon which you raise a perpendicular, which serves for the first line of the flank.
Names of the angles in aFortification.
Angle of the centre, in a polygon, is formed by two radii drawn to the extremities of the same side, or from the centre, terminating at the two nearest angles of the figure.
Angle of a bastion,-Flanked angle,
that which is made by the two faces, being the outermost part of the bastion, most exposed to the enemy’s batteries, frequently called the saliant angle, or point of the bastion.
Angle of the polygon, is made by the concourse of two adjacent sides of a polygon, in the centre of the bastion.
Angle of the triangle, is half the angle of the polygon.
Angle of the shoulder,-Angle of the epaule,
is made by the face and flank of the bastion.
Angle of the flank,-Angle of the curtain
that which is made by, and contained between the curtain and the flank.
Angle of the tenaille,-Flanking angle,
made by two lines fichant, that is, the face of the two bastions extended till they meet in an angle towards the curtain, and is that which always carries its point towards the work.
Dead-angle. Every angle is so called, that points inwards, or is not well defended.
Angle of the ditch, is formed before the centre of the curtain, by the outward line of the ditch.
Angle rentrant,-Re-entering angle,
is any angle whose point turns inwards, or towards the place; that is, whose legs open towards the field.
Saliant angle, is that which points outwards or whose legs open towards the place.
Angle of the complement of the line of defence, is the angle formed by the intersection of the two complements with each other.
Inward flanking angle, that which is made by the flanking-line and the curtain. SeeAngle.
Names of the solid works of aFortification.
Advanced-foss,-Avant-fossé,
or ditch, made at the foot of the glacis: it is but very seldom made, because it is easily taken, and serves for a trench to the besiegers.
Appareille, is that slope or easy ascent which leads to the platform of the bastion, or to any other work, where the artillery, &c. are brought up and carried down.
Approaches, are a kind of roads or passages sunk in the ground by the besiegers, whereby they approach the place under cover of the fire from the garrison.
Area, the superficial content of a rampart, or other work.
Arrow, is a work placed at the saliant angle of the glacis, and consists of two parapets, each about 40 fathoms long; this work has a communication with the covert-way, of about 24 or 28 feet broad, called a caponniere, with a ditch before it of about 5 or 6 fathom, and a traverse at the entrance, of three fathom thick, and a passage of 6 or 8 feet round it.
Banquette, whether single or double, is a kind of step made on the rampart of a work near the parapet, for the troops to stand upon, in order to fire over the parapet: it is generally 3 feet high when double, and 1¹⁄₂ when single, and about 3 feet broad, and 4¹⁄₂ feet lower than the parapet.
Bastion, is a part of the inner inclosure of a fortification, making an angle towards the field, and consists of 2 faces, 2 flanks, and an opening towards the centre of the place, called the gorge: or it is rather a large mass of earth, usually faced with sods, sometimes with brick, but rarely with stone; having the figure described.
With regard to the first invention of bastions, there are many opinions amongst authors. Some have attributed this invention to Zisca, the Bohemian; others to Achmet Bashaw, who having taken Otranto in the year 1480, fortified it in a particular manner, which is supposed to be the first instance of the use of bastions. Those who wrote on the subject of fortification 200 years ago, seem to suppose, that bastions were a gradual improvement in the ancient method of building, rather than a new thought, that any one person could claim the honor of. It is certain, however, that they were well known soon after the year 1500; for in 1546, Tartalea publishedQuesiti & inventioni diverse, in the 6th book of which he mentions, that whilst he resided at Verona (which must have been many years before) he saw bastions of a prodigious size: some finished, and others building: and there is besides, in the same book, a plan of Turin, which was then fortified with 4 bastions, and seems to have been completed some time before.
The great rule in constructing a bastion is, that every part of it may be seen and defended from some other part. Mere angles are therefore not sufficient, but flanks and faces are likewise necessary. The faces must not be less than 50 fathom, nor more than 65. The longer the flanks are the greater is the advantage which can be derived from them. They must therefore stand at right angles with the line of defence. At the same time the disposition of the flanks makes the principal part of a fortification, as on them the defence chiefly depends; and it is this that has introduced the various kinds of fortifying.
The angle of the bastion must exceed 60°; otherwise it will be too small to give room for the guns, and will either render the line of defence too long, or the flanks too short. It must therefore be either a right angle or some intermediate one between that and 60 degrees.
Full bastionsare best calculated for intrenchments, which are thrown up at the gorge, or by means of a cavalier, whose faces are made parallel to those of the bastion at the distance of 15 toises; having its flanks at the distance of 12 toises, and a ditch measuring 5.
Large bastionshave the advantage of small ones, for this palpable reason; thebastion being considered the weakest part of the body of a place, is always attacked; when there is room for troops, cannon and mortars, its natural weakness is greatly remedied.
Gorge of a bastion, the interval between the extremity of one flank and that of the next.
Flat bastion.When a bastion upon a right line is so constructed, that its demi-gorges do not form an angle, it is called a flat bastion.
Gorge of a flat bastion, is a right line, which terminates the distance between two flanks.
Solid bastion,-Full bastion,
A bastion is said to be solid or full, when the level ground within is even with the rampart; that is, when the inside is quite level, the parapet being only more elevated than the rest. Solid bastions have this advantage over others, that they afford earth enough to make a retrenchment, in case the enemy lodge themselves on the top of the bastion, and the besieged are resolved to dispute every inch of ground.
Hollow bastion,-Empty bastion,
is that where the level ground within is much lower than the rampart, or that part next to the parapet, where the troops are placed to defend the bastion. The disadvantage of these kinds of bastions is, the earth being so low, that when an enemy is once lodged on the rampart, there is no making a retrenchment towards the centre, but what will be under the fire of the besiegers.
Detached bastion, is that which is separated or cut off from the body of the place, and differs from a half moon, whose rampart and parapet are lower, and not so thick as those of the place, having the same proportion with the works of the place. Counter-guards with flanks are sometimes called detached bastions.
Cut bastion, is that whose saliant angle or point is cut off, instead of which it has a re-entering angle, or an angle inwards. It is used, either when the angle would, without such a contrivance, be too acute, or when water, or some other impediment, prevents the bastion from being carried to its full extent.
Composed bastion, is when two sides of the interior polygon are very unequal, which also renders the gorges unequal; it may not improperly be called aforced bastion, being as it were forced into that form.
Deformed bastion, is when the irregularity of the lines and angles causes the bastion to appear deformed, or out of shape.
Demi-bastion, is composed of one face only, has but one flank, and a demi-gorge.
Double bastion, is that which is raised on the plane of another bastion, but much higher; leaving 12 or 18 feet between the parapet of the lower, and the foot of the higher; and is sometimes in the nature of a cavalier.
Regular bastion, is that which has its true proportion of faces, flanks, and gorges.
Irregular bastion, is that wherein the above equality of just proportion is omitted.
Barriers, in fortification, a kind of rails to stop the horse or foot from rushing in upon the besieged with violence. In the middle of this kind of defence there is a moveable bar of wood, which opens or shuts at pleasure.
Berm, is a little space or path, of 4 to 8 feet broad, between the ditch and the talus of the parapet; it is to prevent the earth from rolling into the ditch, and serves likewise to pass and repass. As it is in some degree advantageous to the enemy, in getting footing, most of the modern engineers reject it.
Bonnet, in fortification, is a sort of work placed before the saliant angle of the ravelin to cover it: it consists of 2 faces, parallel to the ravelin, or perpendicular to those of the lunette. They are generally made 10 fathom broad at the ends with a ditch of the same breadth, the covert-way 6, and the glacis 20 fathom.
Breach, is on opening or gap made in a wall or rampart, with either cannon or mines, sufficiently wide for a body of troops to enter the works, and drive the besieged out of it.
Practical breach, is that where men may mount, and make a lodgment, and should be 15 or 20 feet wide.
Capital of a work, is an imaginary line which divides that work into two equal parts.
Capital of a bastion, a line drawn from the angle of the polygon to the point of the bastion, or from the point of the bastion to the centre of the gorge. These capitals are from 35 to 40 toises in length, from the point of the bastion to the place where the two demi-gorges meet; being the difference between the exterior and the interior radii.
Caponnieris a passage made in a dry ditch from one work to another: when it is made from the curtain of the body of the place to the opposite ravelin, or from the front of a horn or crown-work, it has a parapet on each side, of 6 or 7 feet high, sloping in a glacis of 10 or 12 toises on the outside to the bottom of the ditch; the width within is from 20 to 25 feet, with a banquette on each side: there is a brick wall to support the earth within which only reaches within 1¹⁄₂ foot of the top, to prevent grazing shot from driving the splinters amongst the defendants.
Caponniereswith two parapets may properly be called double; as there are some made with one rampart only, in dry ditches of the ravelin, and in that ofits redoubt, towards the saliant angles, and to open towards the body of the place.
Caponnieres, made from the body of the place to the out-works, are sometimes arched over, with loop-holes to fire into the ditch. The single ones in the ditch of the ravelin and redoubt are likewise made with arches open towards the place; for by making them in this manner, the guns which defend the ditch before them, can no other way be dismounted than by mines.
Cascanes, in fortification, a kind of cellars made under the capital of a fortification; also subterraneous passages or galleries to discover the enemy’s mines.
Casemate, in fortification, is a work made under the rampart, like a cellar or cave with loop-holes to place guns in it.
Cavaliers, are works, raised generally within the body of the place, 10 or 12 feet higher than the rest of the works. Their most common situation is within the bastion, and they are made much in the same form: they are sometimes placed in their gorges, or on the middle of the curtain, and then are in the form of a horse-shoe, only flatter.
The use of cavaliers is, to command all the adjacent works and country round them: they are seldom or never made, but when there is a hill or rising ground which overlooks some of the works.
Centre, the middle point of any work. From thecentreof a place are drawn the first lines to lay down the form of afortification.
Centre of the bastion, is that point where the two adjacent curtains produced intersect each other.
Citadel, is a kind of fort, or small fortification, of 4, 5, or 6 sides; sometimes joined to towns, &c. Citadels are always built on the most advantageous ground. They are fortified towards the city, and towards the country; being divided from the former by an esplanade, or open place: and serving in one case to overawe the inhabitants; and in the other, not only to hinder the approach of an enemy; but to become a retreat to the garrison, should the town be taken.
Coffers.SeeCoffers.
Commandis when a hill or rising ground overlooks any of the works of afortification, and is within reach of common shot; such a hill is said to command that work. SeeCommand.
Complement of the curtain, is that part of the interior side which forms the demi-gorge.
Complement of the line of defence, is ahorn-workwith acrown-workbefore it. SeeCrown-work.
Cordon, in fortification, is a round projection made of stone, in a semi-circular form, whose diameter is about 1 foot, and goes quite round the wall, and within 4 feet from the upper part.
The cordon being placed on the top of the revetement of the scarp, is a considerable obstacle to the besiegers, when they attempt to storm a place by applying scaling ladders to the scarp.
Covert-wayis a space of five or six toises broad, extending round the counterscarp of the ditch, and covered by a parapet from six to seven feet and a half high, having a banquette: the superior part of this parapet forms a gentle slope towards the country, which terminates at the distance of twenty to twenty five toises; this slope is called the glacis.
Sometimes the covert-way is sunk 2 or 3 feet below the horizon of the field; for, as such works are never made to discover the enemy in their trenches, so this method of lowering the covert-way will give room for the fire of the lower curtain (in works that have one) to scour the esplanade; and the expence of it should be the most material objection against it.
Counter-forts, in fortification, are by some calledbuttresses; they are solids of masonry, built behind walls, and joined to them at 18 feet distance from the centre to centre, in order to strengthen them, especially when they sustain a rampart or terrace.
Counter-guard, in fortification is a work placed before the bastions to cover the opposite flanks from being seen from the covert way. It is likewise made before the ravelins.
When counter-guards are placed before the collateral bastions, they are esteemed of very great use, as the enemy cannot batter them without having first secured the possession of the counter-guards. They were first invented by Pasino, in 1579, and greatly improved by Speckle, in 1589.
Counterscarp, is properly the exterior talus of the ditch, or that slope which terminates its breadth, and is the further side from the body of the place. It is so called from being opposite to the scarp.
Crown-work, in fortification is a kind of work not unlike a crown: it has 2 fronts and 2 branches. The fronts are composed of 2 half bastions and 1 whole one: they are made before the curtain or the bastion, and generally serve to enclose some buildings which cannot be brought within the body of the place, or to cover the town-gates, or else to occupy a spot of ground which might be advantageous to an enemy. They are of such an expence, that they are rarely found in practice. The best use this work can possibly be put to, is to cover 2 joining curtains, when the sides of it will be parallel to the sides of the place, and it should be fortified with the same strength, and in the same manner.
The authors who have written on the subject, have never thought of this useful part; and we often see 2 horn-works put in practice to cover two curtains, where crown-work would do it much cheaperand much better. The crown-work is adopted for the same purposes as the horn-work.
Crowned horn-work, is ahorn-workwith acrown-workbefore it. SeeCrown-work.
Curtain, in fortification, is that part of the body of the place, which joins the flank of one bastion to that of another. The straight curtains have always been preferred to the different designs which have been proposed, of which some have diminished the expence, and (at the same time) the strength of the place, others have somewhat augmented the strength, but greatly diminished its area.
Cuvette,-Cunette,
in fortification, is a small ditch from 15 to 20 feet broad, made in the middle of a large dry ditch, serving as a retrenchment to defend the same, or otherwise to let water into it, when it can be had during a siege.
When there is a cunette, there should be a caponniere to flank it.
Defilement, in fortification, is the art of disposing all the works of a fortress in such a manner, that they may be commanded by the body of the place. It also includes the relative disposition of the works, and the ground within cannon shot, so that the one may be discovered, and the other not observed.
Demi-gorge, is half the gorge, or entrance into the bastion, not taken directly from angle to angle, where the bastion joins the curtain, but from the angle of the flank to the centre of the bastion, or rather the angle the two curtains would make were they protracted to meet in the bastion. Mr. Landmann determines it to be the line which is formed by the prolongation of the curtain meeting the oblique radius.
Demi-lune.SeeRavelin.
Descentsin fortification, are the holes, vaults, and hollow places made by undermining the ground.
Descents into the ditch or fossé, are boyaux or trenches effected by the means of saps in the ground of the counterscarp, under the covert way. They are covered with madriers, or hurdles, well loaded with earth, to secure them against fire. In ditches that are full of water, the descent is made even with the surface of the water; and then the ditch is filled with fagots, fast bound, and covered with earth. In dry ditches thedescentis carried down to the bottom; after which, traverses are made either as lodgments for the troops, or to cover the miner. When the ditch is full of water, thedescentmust be made over its surface; which is done by securing it with blinds or chandeliers, from being enfiladed, or by directing the course of the descent from the point of enfilade in the best way you can.
Detached bastion.SeeBastion.
Detached redoubt.SeeRedoubt.
Ditch, in fortification, is a large deep trench made round each work, generally from 12 to 22 fathom broad, and 15 to 16 feet deep: the earth dug out of it serves to raise the rampart and parapet. Almost every engineer has a particular depth and breadth for ditches; some are for narrow ones and deep, others for broad ones and shallow; and it is most certain that ditches should be regulated according to the situation. In regard to wet and dry ditches, almost all authors have given it in favor of the latter; and we shall only add, that the best of all are those which can either be filled or kept dry at pleasure.
Wet ditches, which have stagnant waters, are liable to great inconveniences. They are said to be well calculated to prevent sudden surprises and assaults; but we are convinced of the contrary, especially during a hard frost. Some again assert, that they stop all communication between ill-disposed persons in the garrison and the besiegers. Every man with the least experience, must be of a different opinion.
Wet ditches might certainly be so constructed, as to let the surface of the water remain 12 or 15 feet above the level of the adjacent country. In which case they would serve as large reservoirs, and not only contribute to the defence of a fortified place, but enrich the grounds by being occasionally let out. The additional value which the neighboring meadows would bear from these seasonable overflowings, might in some degree compensate for the expence of the fortification. During a siege, these waters, with proper management, must give considerable uneasiness to the enemy that invests the place.
To answer this double purpose, the ditch must be separated into several large basons, which might be filled or emptied at discretion, as often as circumstances would require.
Dry ditches.There are some ditches which may be filled at will; and others which cannot, except by extraordinary means. If they should be intended to answer the purpose of agriculture, aqueducts might be constructed, or the waters poured in through artificial channels. In which case the ditches would not require much depth. The glacis might be raised in such a manner as to serve to dam in the body of water, and to afford a second glacis from whence the besieger might be considerably embarrassed.
Ditches that are lined, ditches whose counterscarp is supported, and kept up by a stone or brick wall.
Ditches that are not lined, whose counterscarp is supported by earth covered with sods. These ditches are not so secure as the former, on account of the breadth which must be given to the talus, and by which an enemy might easily surprise a place.
So that ditches in fortification may be briefly distinguished under three separate heads, viz:
Dry ditches, which from the facility with which they may be repaired, and their capability of containing other works proper for their security, are in most instances preferable to any others.
Wet ditchesthat are always full of water, and consequently must have bridges of communication which are liable to be destroyed very frequently during a siege.
Wet ditches are subject to many inconveniences, are ill calculated to favor sallies, and have only the solitary advantage of preventing a surprise.
The third sort of ditch has all the advantages of the other two kinds; if, as we have just observed, it can be so contrived, as to admit water occasionally into the different basons by means of aqueducts, and be drained, as circumstances may require.
Draw-bridge.SeeBridge.
Embrasures.SeeEmbrasure.
Envelope, is a work of earth raised occasionally in the ditch, sometimes like a plain parapet, at others like a small rampart with a parapet to it. Envelopes are generally made before weak places.
Epaulement.SeeEpaulement.
Epaule, or the shoulder of the bastion, the angle made by the union of the face and flank.
Escarp.SeeScarp.
Esplanade.SeeEsplanade.
Exterior side of a fortification, is the distance, or imaginary line drawn from one point of the bastion to that of the next.
Facesof the bastion. SeeBastion.
Faces, of any work, in fortification, are those parts where the rampart is made, which produce an angle pointing outwards.
Face prolonged, that part of the line of defence rasant, which is terminated by the curtain, and the angle of the shoulder.
Fascine.SeeFascines.
Fausse bray, is a low rampart going quite round the body of the place; its height is about 3 feet above the level ground, and its parapet is about 3 or 4 fathom distant from that of the body of the place. These works are made at a very great expence: their faces are very easily enfiladed, and their flank of course is seen in reverse: the enemy is under cover the minute he becomes master of them; and a great quantity of shells which may be thrown into them, and must of necessity lodge there, will go near to make a breach, or at worst to drive every one out. Hence they are liable to do more harm than good, and contribute no way to the defence of the place. M. Vauban only makes them before the curtains, and as such calls them tenailles.
Flanks, in fortification, are, generally speaking, any parts of a work, which defend another work along the outsides of its parapets.
Flank of the bastion, is the part between the face and the curtain; the flank of one bastion serves to defend the ditch before the curtain and face of the opposite bastion.
Flanking, is the same thing in fortification, as defending.
Retired flanks, are those made behind the line which joins the extremity of the face and the curtain, towards the capital of the bastion.
Concave flanks, are those which are made in the arc of a circle.
Direct, or grazing flank, is that which is perpendicular to the opposite face produced, and oblique or fichant, when it makes an acute angle with that face.
Second flank.When the face of a bastion produced does not meet the curtain at its extremity, but in some other point, then the part of the curtain between that point and the flank, is called the second flank. The modern engineers have rejected this method of fortifying. SeeFlank.
Flêche, a work of two faces, often constructed before the glacis of a fortified place, when threatened with a siege, in order to keep the enemy as long at a distance as possible.
Gallery, is a passage made under ground, leading to the mines: galleries are from 4¹⁄₂ to 5 feet high, and about 3¹⁄₂ or 4 feet broad; supported at top by wooden frames, with boards over them.
Genouilliere, the undermost part of the rampart of a battery, or that part from the platform to the sole of the embrasures.
Glacis, is the part beyond the covert way, to which it serves as a parapet, and terminates towards the field in an easy slope at any required number of fathoms distance. Sometimes double glacis are made parallel to the esplanade, and at the distance of 16, or 20 fathoms.
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. SeeRavelins.
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 beinsulted, 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, SeeSiege.
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.
Lunettesin 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.SeeWorks.
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.SeeSiege.
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.
Placeis 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.SeeSiege.
Pits, orponds, 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. SeeProfiles.
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. SeeGorges.
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 thecordon.
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.
Rideauis 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.SeeSiege.
Scarp, is, properly speaking, any thing high and steep, and is used infortificationto 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.
Sillonmeans 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.
Talussignifies 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 banquetteis 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.
Tenaillesare 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.
Tenaillonsare 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 theterre pleinethat the garrison pass and repass; it is also the passage of the rounds.
Tower bastionsare 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 calledtambours.
Traversesare 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 theworksof a place.
Out-works.All detachedworksin a fortification are so called. SeeDehors.
Zig-Zag.SeeSiege.
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.
FieldFortificationis 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 offortification, 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, constructeden 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 introus-de-loupor wolf-holes, must be 6 feet long, 4 inches thick, and sharp at the top.
7. The beams belonging to acheval-de-frizemust 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. Thesechevaux-de-frizesare 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 fieldFortification.
Bridge heads, ortêtes 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 ofheads 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.