Abbatis A defensive barricade or row of obstructions made up of closely spaced felled trees, their tops toward the enemy, their branches trimmed to points and interlaced where possible.
Banquette A continuous step or ledge at the interior base of a parapet on which defenders stood to direct musket fire over the top of the wall. A fire step.
Bastion A projection of the curtain wall, usually at the corners, made up of four sides, two faces and two flanks, which better enabled a garrison to defend the ground adjacent with crossfire.
Battery An emplacement for artillery.
Berm A line of wooden stakes or logs, 6ft–8ft long, planted in the middle of a ditch and pointing vertically.
Breastwork See Parapet.
Casemate A mortar-proof or shellproof chamber located within the walls of defensive works; generally pierced with openings for weapons, loopholes for muskets, or embrasures for cannon.
Chandelier A movable parapet placed over the ground, made of wooden frames, on which fascines or other filling material were laid.
Cordon The coping or top course of a scarp or a rampart, sometimes of different coloured stone and set proud from the rest of the wall. The point where a rampart stops and a parapet begins.
Counterguard A defensive work built in a ditch in front of a bastion to give it better protection.
Counterscarp The outer side of a ditch or moat. See also Scarp.
Covered way A depression, road or path in the outer edge of a fort’s moat or ditch, generally protected from enemy fire by a parapet, at the foot of which might be a banquette enabling the coverage of the glacis with musketry.
Cunette A furrow located in the bottom of a dry ditch for the purpose of drainage.
Curtain The wall of a fort between two bastions.
Demi-bastion A half-bastion with only one face and one flank.
Demi-lune A triangular-shaped defensive work built in a ditch in front of a bastion or a curtain wall. Also termed a Ravelin.
Ditch A wide, deep trench around a defensive work. When filled with water, it was termed a moat or wet ditch; otherwise a dry ditch or fossé.
Embrasure An opening in a wall or parapet allowing cannon to fire through it, the gunners remaining under cover. The sides of the embrasure were called cheeks, the bottom the sole, the narrow part of the opening the throat, and the wide part the splay.
En barbette An arrangement for cannon to be fired directly over the top of a low wall instead of through embrasures.
Enfilade fire Fire directed from the flank or side of a body of troops, or along the length of a ditch, parapet, or wall. Guns in the flank of a bastion can direct enfilade fire along the face of the curtain.
Epaulement A parapet or work protecting against enfilade fire.
Fascines Long bundles of sticks or small-diameter tree branches bound together for use in revetments, for stabilizing earthworks, filling ditches, etc.
Flèche A field fortification work of two faces, usually raised.
Fossé or foss See Ditch (dry).
Fraise A defense of closely placed stakes or logs, 6ft–8ft long, driven or dug into the ground and sharpened; arranged to point horizontally or obliquely outward from a defensive position.
Gabion A large, round, woven wicker cylinder intended to be set in place and filled with earth, sand, or stones.
Gallery An interior passageway or corridor that runs along the base of a fort’s walls.
Gate A main entrance of a fortress.
Glacis A broad, gently sloped earthwork or natural slope in front of a fort, separated from the fort proper by a ditch and outworks and so arranged as to be swept with musket or cannon fire.
Gorge The interval or space between the two curtain angles of a bastion. In a ravelin, the area formed by the flanked angle and either left open or enclosed.
Guardhouse The headquarters for the daily guard.
Guérite A small lookout watchtower, usually located on the upper outer corner of a bastion.
Half-bastion See Demi-bastion.
Hornwork A work made up of a bastion front, two half-bastions and a curtain, and two long sides termed branches.
Loopholes Small openings in walls or stockades through which muskets are fired.
Machicoulis Projections in old castles and over gates, left open above to throw stones etc. on enemies below.
Magazine A place for the storage of gunpowder, arms, or goods generally related to ordnance.
Merlon The solid feature between embrasures in a parapet.
Moat See Ditch.
Orgue See Portcullis.
Outwork An outer defense, inside the glacis but outside of the body of the place. A ravelin is an outwork.
Palisade A high fence made of stakes, poles, palings, or pickets, supported by rails and set endwise in the ground. See Stockade.
Parapet A breastwork or protective wall over which defenders, standing on banquettes, fire their weapons.
Portcullis A timber or iron grating that can be lowered to close the gates of a fortress.
Postern A passage leading from the interior of a fortification to the ditch.
Rampart The mass of earth, usually faced with masonry, formed to protect an enclosed area.
Ravelin An outwork consisting of two faces forming a salient angle at the front and a flank angle to the rear that was usually closed at the gorge. Ravelins are separated from the main body of the place by ditches and function to protect curtains. Also called a Demi-lune.
Redoubt An enclosed fortification without bastions.
Revetment The sloping wall of stone or brick supporting the outer face of a rampart.
Sallyport A passageway within the rampart, usually vaulted, leading from the interior of a fort to the exterior, primarily to provide for sorties.
Sap A trench and parapet constructed by besiegers to protect their approaches toward a fortification.
Scarp The interior side of a ditch or the outer slope of a rampart. See also Counterscarp.
Stockade A line or enclosure of logs or stakes set upright in the earth with no separation between them, to form a barrier eight or more feet high. Stockades were generally provided with loopholes. The loopholes were reached by banquettes or elevated walks. See also Palisade.
Tabby A cement-like building material made up of ground oyster shells, lime, and sand, mixed with salt water. Used especially in the southern colonies.
Traverse A parapet or wall thrown across a covered way, a terreplein, a ditch, or other location to prevent enfilade or reverse fire along a work.
Trou de loup A usually small pit in the form of an inverted cone, dug as an obstacle and having a pointed stake in the middle.