FORT

, a little castle or fortress; or a place of small extent, fortified either by nature or art.

The Fort is usually encompassed with a moat, rampart, and parapet, to secure some high ground, or passage of a river; to make good or strengthen an advantageous post; or to fortify the lines and quarters of a siege.

Field Fort, otherwise called Fortin, or Fortlet, and sometimes Sconce, is a small Fort, built in haste, for the defence of a pass or post; but particularly constructed for the defence of a camp in the time of a siege, where the principal quarters are usually joined, or made to communicate with each other, by lines defended by fortins and redoubts. Their figure and size are various, according to the nature of the situation, and the importance of the service for which they are intended; but they are most commonly made square, each side about 100 toises, the perpendicular 10, and the faces 25; the ditch about this Fort may be 10 or 12 toises wide; the parapet is made of turf, and fraised, and the ditch pallisadoed when dry. There may be made a covert-way about this Fort, or else a row of pallisades might be placed on the outside of the ditch. Some of these are fortified with bastions, and some with demibastions.——A Fort differs from a citadel, as this last is erected to command and guard some town; and from a redoubt, as it is closed on all sides, while the redoubt is open on one side.

Royal Fort, is one whose line of defence is at least 26 fathoms long.

Star Fort, is a sconce or redoubt, constituted by reentering and saliant angles, having commonly from sive to eight points, and the sides flanking each other.

Forts are sometimes made triangular, only with half bastions; or of various other figures, regular or irregular, and sometimes in the form of a semicircle, especially when they are situated near a river, or the sea, as at the entrance of a harbour, for the convenience of firing at ships quite around them on that side. In the construction of all Forts, it should be remembered, that the figure of fewest sides and bastions, that can probably answer the proposed defence, is always to be preferred; as works on such a plan are sooner executed, and with less expence; besides, fewer troops will serve, and they are more readily brought together in case of necessity.

, called also Military Architecture, is the art of fortifying or strengthening a town or other place, by making certain works around it, to secure it and defend it from the attacks of enemies.

Fortification has been undoubtedly practised by all nations, and in all ages; being at first doubtless very rude and simple, and varying in its nature and manner, according to the mode of attack, and the weapons made use of. Thus, when villages and towns were first formed, it was found necessary, for the common safety, to encompass them with walls and ditches, to prevent all violence and sudden surprises from their neighbours. When offensive and missive weapons came to be used, walls were made as a defence against the assailants, and look holes or loop holes made through the walls to annoy the enemy, by shooting arrows &c through them. But finding that as soon as the enemy got close to the walls, they could no longer be seen nor annoyed by the besieged, these added square towers along the wall, at proper distances from each other, so that all the intervening parts of the wall might be seen and defended from the adjacent sides of the towers. However, this manner of inclosing towns was found to be rather imperfect, because there remained still the outer face of the towers which fronted the field, that could not be seen and defended from any other part. To remedy this imperfection, they next made the towers round instead of square, as seeming better adapted both for strength to resist the battering engines, and for being defended from the other parts of the wall. Nevertheless, a small part of these towers still remained unseen, and incapable of being defended, for which reason they were again changed for square ones, as before, but with this difference, that now they presented an angle of the square outwards to the field, instead of a face or side; and thus such a disposition of the works was obtained, as that no part could be approached by the enemy without being seen and attacked.

Since the use of gun-powder, it has been found necessary to add thick ramparts of earth to the walls, and the towers have been enlarged into bastions, as well as many other things added, that have given a new appearance to the whole art of defence, and the name of Fortification, on account of the strength afforded by it, which was about the year 1500, when the round towers were changed into bastions.

But notwithstanding all the improvements made in this art since the invention of gun-powder, that of attacking is still superior to it: the superiority of the besiegers' fire, together with the greater number of men, soonet or later compels the besieged to submit. A special advantage was added to the art of attacking by M. Vauban, at the siege of Ath, in the year 1697, viz, in the use of ricochet firing, or at a low elevation of the gun, by which the shot was made to run and roll a great way along the inside of the works, to the great annoyance of the besieged.

The chief authors who have treated of Fortification, since it has been considered as a particular art, are the following, and mostly in the order of time: viz, La Treille, Alghisi, Marchi, Pasino, Ramelli, Cataneo, and Speckle, who, as Mr. Robins says, was one of the greatest geniuses that has applied to this art: he was architect to the city of Strasburgh, and died in the year 1589: he published a treatise on Fortification in the German language, which was reprinted at Leipsic in 1736. Afterwards, Errard, who was engineer to Henry the Great of France; Stevinus, engineer to the prince of Orange; with Marolois, the chevalier de Ville, Lorini, Coehorn, the count de Pagan, and the marshal de Vauban; which last two noble authors have contributed greatly to the perfection of the art; besides Scheiter, Mallet, Belidor, Blondel, Muller, Montalambert, &c. Also a list of several works on the art of Fortification may be added, as follows: viz, | Melder's Praxis Fortificatoria: Les Fortifications du Comte de Pagan: L'Ingénieur Parfait du Sieur de Ville: Sturmy's Architectura Militaris Hypothetical.: Blondel's Nouvelle Maniere de Fortifier les Places: The Abbé de Fay's Veritable Maniere de Bien Fortifier: Vauban's Ingénieur François: Coehorn's Nouvelle Fortification tant pour un Terrain bas & humide, que sec & elevé: Alexander de Grotte's Fortification: Donatus Roselli's Fortification: Medrano's Ingénieur François: The chevalier de St. Julien's Architecture Militaire: Lansberg's Nouvelle Maniere de Fortifier les Places: An anonymous treatise in French, called Nouvelle Maniere de Fortifier les Places, tirée des Methodes du chevalier de Ville, &c: Ozanam's Traité de Fortification: Memoires de l'Artillerie de Surirey de St. Remy: Muller's treatises of Elementary and Practical Fortification: and Montalambert's Fortification Perpendiculaire.

Maxims in Fortification. From the nature and circumstances of this art, certain general rules, or maxims, have been drawn, and laid down. These may indeed be multiplied to any extent, but the principal of them, are the following: viz,

1. That the manner of fortifying should be accommodated to that of attacking. So that no one manner can be assured always to hold, unless it be assured that the manner of besieging is incapable of being altered. Also, to judge of the perfection of a Fortification, the method of besieging at the time when it was built must be considered.

2. All the parts of a Fortification should be equally strong on all sides, where there is equal danger; and they should be able to resist the most powerful machines used in besieging.

3. A Fortification should be so contrived, as to be defended with the fewest men possible: which confideration, when well attended to, saves a great deal of expence.

4. That the defendants may be in the better condition, they must not be exposed to the enemies' artillery; but the aggressors must be exposed to theirs. Hence,

5. All the parts of a Fortification should be so disposed, as that they may defend each other. In order to this, every part ought to be flanked, i. e. seen sideways, capable of being seen and defended from some other part; so that there be no place where an enemy can lodge himself, either unseen, or under shelter.

6. All the campaign around must lie open to the defendants; so that no hill or eminence must be allowed, behind which the enemy might shelter himself from the guns of the Fortification; or from which he might annoy them with his own. Hence, the fortress is to command all the place round about; and consequently, the outworks must all be lower than the body of the place.

7. No line of defence must exceed the point-blank musket-shot, which is from 120 to 150 fathoms.

8. The more acute the angle at the centre, the stronger is the place; as consisting of the more sides, and consequently more defensible.

9. All the defences should be as nearly direct as possible.

10. The works that are most remote from the centre of the place, ought always to be open to those that are more near.

These are the general laws and views of Fortification. As to the particular ones, or such as respect the several members or parts of the work, they are given under those articles respectively.

Fortification is either theoretical or practical.

Thcoretical Fortification, consists in tracing the plans and profiles of a work on paper, with scales and compasses; and in examining the systems proposed by different authors, to discover their advantages and defects. And

Practical Fortification, consists in forming a project of a work according to the nature of the ground, and other necessary circumstances, tracing it on the ground, and executing the project, together with all the military buildings, such as magazines, storehouses, bridges, &c.

Again, Fortification is either Defensive or Offensive.

Defensive Fortification is the art of defending a town that is besieged, with all the advantages the Fortification of it will admit. And

Offensive Fortification is the same with the attack of a place, being the art of making and conducting all the different works in a siege, in order to gain possession of the place.

Fortification is also used for the place fortified; or the several works raised to defend and flank it, and keep off the enemy.

All Fortifications consist of lines and angles, which have names according to their various offices. The principal lines are those of circumvallation, of contravallation, of the capital, &c. The principal angles are those of the centre, the flanking angle, flanked angle, angle of the epaule, &c.

Fortifications are either durable or temporary.

Durable Fortification, is that which is built and intended to remain a long time. Such are the usual Fortifications of cities, frontier places, &c. And a

Temporary Fortification, is that which is erected on some emergent occasion, and only for a short time. Such are field-works, thrown up for the seizing and maintaining a post, or passage; those about camps, or in sieges; as circumvallations, contravallations, redoubts, trenches, batteries, &c.

Again, Fortifications are either regular or irregular. A

Regular Fortification, is that in which the bastions are all equal; or which is built in a regular polygon, the sides and angles of which are usually about a musket shot from each other. A Regular Fortification, having the parts all equal, has the advantage of being equally defensible; so that there are no weak places. And an

Irregular Fortification, is that in which the bastions are unequal, and unlike; or the sides and angles not all equal, and equidistant.

In an Irregular Fortification, the defence and strength being unequal, it is necessary to reduce the irregular shape of the ground, as near as may be, to a regular figure: i. e. by inscribing it in an oval, instead of a circle; so that one half may be similar and equal to the other half.|

Marine Fortification, is sometimes used for the art of raising works on the sea coast &c, to defend harbours against the attacks of shipping.——See a neat treatise on Marine Fortisication, at the end of Robertson's Elements of Navigation.

There are many modes of Fortification that have been much esteemed and used; a small specimen of a comparative view of the principal of these, is represented in plate x, viz, those of Count Pagan, and Mess. Vauban, Coehorn, Belidor, and Blondel; the explanation of which is as follows:

A Half Bastions.

B Ravelin and Counterguard.

C Counterguards before the bastions.

D The Ditch.

E The Glacis.

G The place of Arms.

H Retired Flanks.

a Line of Defence.

b Angle of the Bastion, or Flanked angle.

c Angle of the Shoulder.

d Angle of the Flank.

e Saliant Angle.

f Face of the bastion.

g The Flank.

h The Curtain.

i Tenailles.

k Traverses in the covert way.

1 Concave Flanks.

2 The Curtains.

3 Redoubts in the re-entering angles.

4 Traverses.

5 Stone lodgments.

6 Round Flanks.

7 Redoubt.

8 Coffers planked on the sides, and above covered overhead with a foot of earth.

I Cavaliers.

K Rams-horns, or Tenailles.

L Retrenchments within the detached bastions.

M Circular Curtain.

N The Ravelin.

P Lunettes with retired batteries.

Q Redoubt.

R Detached Redoubt.

S An Arrow.

P Small Traverses.

I Retired Battery.

m Lunettes.

n Ravelin, with Retired Bastion.

o Orillons.

Another, or new method of Fortification has lately been proposed by M. Montalambert, called Fortification Perpendic<*>laire, because the faces of the works are made by a series of lines running zigzag perpendicular to one another.

Profile of a Fortification, is a representation of a vertical section of a work; serving to shew those dimensions which cannot be represented in plans, and are necessary in the building of a Fortification. The names and dimensions of the principal parts are as follow (see fig. 8, pl. vii), where the numbers or dimensions are all expressed in feet.

AB The level of the ground plane,

AC = 27,

CD = 18, and CW = 16 1/2; also DN is paral. to AB.

DE = 30,

EF = 2, FG = 3, GH = 3, HI = 4 1/2, IL = 1 1/2,

LK = 18, KM = 2 1/2, NP = 36, NO = 5,

PR = 7,

RS = 1, ST = 12 or 18, OV = 9, Pn = 120,

mz = 3, nu = 3, mc = 30, cd = 2,

de = 3, ef = 3, fl = 4 1/2, rg = 120, lh = 1.

AW the interior talus or slope of the rampart,