The Terminology of a Fortress

Every effort has been made to provide accurate definitions, however it should be noted that no two Forts are exactly the same and terms were often modified and definitions stretched to best fit in unique circumstances.

  • A – D

    Advanced work: any work of fortification located outside the glacis, yet within musketry range.

    Angle of defense: the angle formed by a line of defense and a flank.

    Banquette*: a continuous step or ledge at the base of a parapet, on which defenders stood to fire over the top of the wall.

    Bastion*: a projection in the enceinte, comprised of two faces and two flanks, which enabled the garrison to defend the ground adjacent to the enceinte.

    Bombproof: a structure designed to provide security against artillery fire.

    Branch gallery: a small tunnel dug from a listening gallery to intercept enemy miners.

    Breast height: a wall, chest high, from behind which musketry fire could be directed against an approaching army.

    Capital of the bastion: an imaginary line connecting the point of the bastion and the point of the corresponding angle of the polygon of fortification.

    Caponnier: a passage across a dry ditch, formed by two parapets which sloped down to the level of the ditch. Generally there was a banquette on each side of the passage from which the ditch could be defended. The term also denotes an architectural form extending from the main body of the place for the purpose of providing for flanking fire.

    Casemate*: a bombproof enclosure, generally located under the rampart and terreplein, for the purpose of housing cannon which fired through embrasures in the scarp. Casemates were also used as quarters, magazines, etc. In permanent fortifications they were vaulted, but in impermanent works they sometimes had trabeated structures.

    Cavalier: in fortification, a raised work where artillery was placed to command the surrounding works or country. It was commonly placed on the terreplein of a bastion or curtain.

    Coping: the top course of a parade face wall revetment.

    Cordon*: the top course of the scarp, normally designed to protect the wall from weathering. In plan, the line created by the cordon was termed the “magistral line.”

    Counterfire room: see counterscarp gallery.

    Counterfort: interior buttress, used to strengthen revetment walls.

    Countermine gallery: underground tunnel excavated by defenders for the purpose of intercepting the mines of besieging forces and destroying their works. From these listening galleries could be excavated.

    Counterscarp*: the exterior side of the ditch—the side of the ditch away from the body of the place.

    Counterscarp gallery: a work located behind the counterscarp, from which the ditch could be defended with reverse fire.

    Covered way*: a road around a fortification between the ditch and the glacis. It was protected from enemy fire by a parapet, at the foot of which was generally a banquette enabling the coverage of the glacis with musketry. In addition to its function as an outer line of defense, it served as a place for sorties to assemble.

    Coverface: a work comprised of two faces forming a salient angle, placed before bastions or ravelins, but separated from them, to protect their faces from cannon missiles.

    Crenated gallery: See reverse fire gallery

    Crotchet: (technically, crotchet du glasis): a passage around traverse on the covered way.

    Curtain*: a section of a bastioned fortification that lies between two bastions.

    Curtain angle: in plan, the angle formed between the curtain and the flank.

    Deblais: earth or stone excavated from the ditch to form the ramparts, terreplein, etc.

    Defilade (defilement): the arrangement of fortifications to minimize the effect of plunging cannon fire from a nearby eminence.

    Demi-bastion: a bastion with only one face and one flank.

    Demi-gorge: a segment lying on the prolongation of the line of the curtain and defined by the point of the curtain angle and the intersection of the line of the curtain with the capital of the bastion.

    Detached work: in general, a work beyond the range of musketry from the body of the place, yet functionally related to its defense.

    Ditch*: a wide, deep trench around a defensive work. When filled with water, it was termed a “wet ditch,” otherwise it was called a “dry ditch.”

    Drawbridge: a bridge across a deep ditch which may be raised to isolate the body of the place from the covered way or other approach.

  • E – H

    Embrasure*: an opening in a wall or parapet through which cannon were fired. The sides, generally splayed outward, were termed “cheeks;” the bottom was called the sole;” the narrow part of the opening, the “throat;” and the widening, the “splay.”

    En barbette: an arrangement for cannon wherein they were mounted on high platforms or carriages so that they fired over a parapet rather than through embrasures.

    En casemate: cannon mounted in casemates.

    Enceinte: the main works of fortification—walls, ramparts, and parapets—forming the primary enclosure of a fort or fortress.

    En Cremaillere: a work formed in a series of offsets.

    Enfilade fire: fire directed along the length of a ditch, parapet, wall, etc.

    Escalade: an attack where a fortification is stormed and ladders are used to ascend the walls.

    Exterior ditch: the outermost ditch between an exterior front and the covered way.

    Exterior front: a front of fortification separated from the main body of the place by a ditch.

    Exterior slope: a steep earth incline on the exterior side of a rampart, which connected the superior slope with the scarp.

    Face of the bastion: the section of any bastion between the flanked angle and shoulder angle. In a regular bastion it was one of the two sides of the bastion, which formed a salient angle pointing outwards and which was situated on the lines of defense.

    Flank of the bastion: the section of the bastion lying between the face and the curtain, from which the ditch in front of the adjacent curtain and the flank and face of the opposite bastion were defended.

    Flanked angle: the angle formed by two faces of a bastion or ravelin. It is also called the “salient,” or “point of the bastion,” or “point of the ravelin.”

    Fort: a work established for the defense of a land or maritime frontier, of an approach to a town, or of a pass or river. Although the term originally denoted a small fortification garrisoned by troops, in North America it was used to designate virtually any establishment—civil or military—associated with protection from adversaries, regardless of whether any actual fortifications were included.

    Fortification: the art of building works for defense or attack which, through their form and construction, enabled their occupants to resist for a considerable length of time assaults by superior forces.

    Front of a Fortification: the works—flanks, faces, curtains, etc.—associated with a single side of the polygon of fortification. Thus, one front of a bastioned fort consisted of two half bastions, a curtain and related outworks.

    Gate: a main entrance in the enceinte of a castle, fort, or fortress.

    Glacis*: a broad, gentle-sloped earthwork built-up outside the covered way. At the covered way, it terminated against a parapet, and, in the direction of the field, it sloped gently downward until it generally blended into the natural level of the ground.

    Gorge: in a bastion, the interval or space between the two curtain angles. In other works that were open at the rear, it denoted the opening.

    Hotshot furnace: an oven for heating cannon shot, red hot, before firing.

  • I – M

    Interior ditch: the wide depression separating the enceinte from the exterior front.

    Interior slope: the inner side of a parapet, generally connecting the superior slope with a retaining wall in front of the banquette.

    Land front: a front of a fortification designed to defend against a land-based attack.

    Line of defense: the line extending from an angle in the exterior polygon of fortification, or flanked angle of the bastion, to the opposite flank.  It determined the position of the face of the bastion relative to the flank which would defend it.

    Listening gallery*: a tunnel under various parts of earth fortifications formed with walls and vaulting of masonry extending from within which the sounds of tools of enemy miners could be detected.

    Loophole*: a small opening in a wall or stockade through which small arms were fired.

    Magazine: a place for the storage of gunpowder, arms, provisions, or goods.

    Main body the work: see the body of the work.

    Mine: in fortification, a subterranean tunnel excavated by besiegers under a fortification for the purpose of destroying a section of the work with explosives or other means.

  • O – S

    Outwork:  a work inside the glacis but outside the body of the place.

    Pan coupé: technically, a “broken” corner; at Fort Adams the short section of the enceinte between two longer southeast and southwest interior fronts.

    Parade: an area, usually centrally located, where troops were assembled for drill and inspection.

    Parade face: the wall or side of an enceinte next to the parade ground.

    Parapet*:  in fortification, a work of earth and/or masonry forming a protective wall over which defenders fired their weapons.  In buildings, a perimeter wall extending above a roof or platform.

    Pas de souris: small steps between the ditch and covered way.

    Perpendicular: a line located at the center of a side of a polygon of fortification, drawn inward, on which a measurement is established to determine the position of the lines of defense.

    Pintle: an upright metal pivot pin about which a carriage swivels.

    Polygon of fortification:  a plane geometric form on which fronts of fortification were traced.

    Portcullis: a sliding timber or iron grate which was suspended over a gateway and which was raised or lowered in vertical channels to close the entrance.

    Postern:  a passage leading from the interior of a fortification to the ditch.

    Profile: the outline of a vertical section of a work.

    Rampart*: a mass of earth, usually formed with material excavated from the ditch, to protect the enclosed area from artillery fire and to elevate defenders to a commanding position overlooking the approaches to a fort.

    Redoubt: an enclosed fortification without bastions.

    Reentering angle: an angle pointing toward the interior part of a fortification.

    Reentering place of arms*: a space along the covered way formed outside the reentering angle of the counterscarp by providing a salient in the parapet.  Its function was to provide space for forming sorties and a means for flanking defense of the glacis.

    Remblais: earth used to make a fill or form fortifications such as the rampart and terreplein.

    Reverse fire: fire directed over the near side of a work from the opposite side, or to the rear of a line.

    Reverse fire gallery*: counterscarp gallery with loopholes.

    Revetment: the facing of the sides of a ditch or parapet.

    Salient: an angular work which projects outward from the interior.

    Salient angle: an angle pointing outward.

    Salient place of arms: a space along the covered way formed by rounding the trae of the counterscarp opposite the flanked angle of the bastion.

    Sallyport*: a passage, either open or covered, from the covered way to the country; or a passage under the rampart, usually vaulted, from the interior of a fort to the exterior, primarily to provide for sorties.

    Sap: a trench and parapet effected by besiegers to protect their approaches toward a fortification.

    Scarp*: the interior side of the ditch.  It was also sometimes termed “escarp.”

    Shoulder angle: the interior angle formed by the meeting of a flank and a face of a bastion or other work.

    Shoulder of the bastion: the corner formed by the intersection of the face and flank of a bastion.

    Seige: an organized, systematic attack on a fort or fortress.

    Sortie: a sudden attack on besiegers by troops from a defensive work.  The main objective was to destroy siege works that had been effected by the aggressors.  Also called a sally.

    Superior slope: the top surface of an earth parapet, which slanted downward toward the country, the slope of which was inclined sufficiently to allow defenders to cover all the ground outside the ditch; the slope between the exterior and interior slopes.

    System of fortification: a formulized arrangement and proportioning of various elements of fortification, usually identified with inventor of the combination or with the country in which it was extensively used.

  • T – V

    Tenaille*: a work constructed in a main ditch between bastions, in front of a curtain erected to protect the curtain from the battering of enemy cannon fire.

    Terreplain*: technically, an earth plane comprising a level space on the rampart between the parapet and parade face.  However, in most nineteenth-century American forts the platform was paved with bricks.

    Trace: the outlines of the horizontal configurations of a fortification.

    Traverse:  a parapet thrown across a covered way, a terreplein, or other location to prevent enfilade or reverse fire along a work.

    Traverse platform: a platform which moved on tracks in an arc about a pintle.  The gun carriage was mounted on the platform.

    Traverse circle: the circle on which the wheels of a traversing carriage rode.

    Vault: an arched work of masonry, forming the roofs over the casemates, galleries or other spaces.  Among the types of vaults found at Fort Adams are: barrel, parabolic and groined vaults.

    Vents: in a casemate a flue or vertical opening intended to allow smoke to escape from the casemates.