Abatis or abattis - felled trees, arranged in the form of a hedge with trunks aligned and anchored in shallow ditches and with sharpened branches interlaced and pointing toward the enemy. Its purpose was to prevent surprise and to delay an attacking force within range of defensive weapons.
Advanced Works - fortifications in advance of but still within firing range of the main works.
Angle - point where two straight faces of a fortification meet. Salient angles point toward the enemy; re-entering angles (reentrants) point away from the enemy.
Apex - foremost angle of a fortification.
Approach – a trench dug to get closer to the enemy line, called a sap in siege operations.
Banquette or Firing Step – a shelf dug behind a parapet that allowed a defender to step up from the ditch to fire over the parapet, then step back down under cover to reload. A banquette was only necessary when the parapet was higher than a man’s armpits. A common feature associated with prepared fortifications, its outline is often blurred or covered by earth eroding from the parapet.
Balk – a narrow barrier of earth within the ditch of an earthwork that was purposely left un-dug. Balks often show divisions between regiments in the line.
Barbette - artillery positioned to fire over the parapet rather than through an opening in it. (See embrasure). A cannon firing en barbette had an unrestricted (180°) field of fire, but the gunners were exposed to view. A cannon firing en embrasure had a restricted (45°) field of fire but the gunners were protected by the parapet. A barbette gun might be raised to fire over the parapet by means of a large carriage or by a gun platform built up to the appropriate height. See gun platform.
Bastion - a standard component of artillery fortifications into the twentieth century. A bastion was an angular work in the form of a lunette that projected outward from the main trace of the fortification. Its purpose was to eliminate dead ground by providing enfilade fire fronting an adjacent curtain. A bastion consisted of four parts: two salient faces oriented towards the enemy, and two reentering flanks that directed fire sideways across the faces of adjacent bastions. A curtain (or curtain wall) connected two or more bastions.
Bastioned Fort – an enclosed earthwork with bastions in the angles to provide fire along the fronts of the connecting parapets.
Battery - an artillery unit or a fortification designed to defend an artillery unit.
Berme or Berm – narrow ledge or shelf left at grade to separate the scarp of the ditch and the exterior slope of the parapet. When constructing large defenses, workers stood on the berm to heft earth up onto the parapet. The berm was often left to retard slumping of the parapet, but many engineers felt that it assisted attackers in scaling the parapet and had it pared down after construction. Soil eroding from the parapet will typically blur a berm’s outline.
Blockhouse - building constructed of heavy logs in the shape of a square, rectangle, or cross, to serve as a strong point for infantry or artillery. A ditch was often excavated around the exterior with the spoil thrown up against the wooden structure as a protection against fire and gunfire. Often part of the first floor of a blockhouse was below ground, while the upper floor, pierced with loopholes and embrasures, was built with an overhang so that defenders could fire down around the base of the structure. Blockhouses were used to defend railroad trestles, bridges, and depots, or served as a “keep” or place of final refuge in a larger fortress or stockade. The excavations associated with many blockhouses survive, although timbers were often scavenged for other uses. Some had brick or stone flooring and fireplaces.
Bombproof – a log or plank room or “bunker” covered over with earth to protect troops from artillery fire. A surviving bombproof appears as a large mound of earth, sometimes with a depression in the top where underlying timbers have collapsed or in the side where the entrance used to be. From visible remains, it is difficult to tell if a mound was a bombproof or a structure to store powder and ammunition. See magazine. A single mound within an artillery fortification is likely to have been a magazine, because powder was protected before men.
Boyau or Boyaux -- a communication trench.
Breaching Battery – a battery constructed during siege operations to enfilade a portion of the enemy’s defenses or to batter down the enemy’s walls or parapets.
Breastwork – usually a fieldwork no higher than a man’s chest. A breastwork could be constructed of earth, logs, stones, or whatever else might be at hand, such as cotton bales. The term is used very generically.
Capital – the imaginary line that bisects the salient angle of a work.
Cavalier – a portion of a fortification built higher and stronger than surrounding works to serve as a “keep” or place of final refuge.
Cheek - side of an embrasure. Often shaped by gabions or sandbags.
Caponière - a redan projecting from the front of a curtain wall to enable infantry or artillery to provide enfilade fire into the ditch.
Chevaux-de-frise – obstacles built of logs with projecting spikes, joined together by chains or ropes.
Circumvallation is a line of fortifications, built by the attackers around the beseiged fortification facing towards an enemy fort (to protect the besiegers from sorties by its defenders and to enhance the blockade. The resulting fortifications are known as 'lines of circumvallation'. Lines of circumvallation generally consist of earthen ramparts and entrenchments that encircle the besieged city or fortress. The line of circumvallation can be used as a base for launching assaults against the besieged city or for constructing further earthworks nearer to the city.
Communication Trench – a ditch and parapet that connect one part of an entrenchment with another to move troops and supplies. These were sometimes simple trenches, serving as arteries to direct reserves to some portion of the line. Called a covered way if deep enough to conceal movement.
Continuous Line – a line of fortifications presenting a solid front to the enemy. Parapets connect all of the artillery strong points on the line.
Contravallation may be constructed in cases where the besieging army is threatened by a field army allied to an enemy fort. This is a second line of fortifications outside the circumvallation, facing away from an enemy fort. The contravallation protects the besiegers from attacks by allies of the city's defenders and enhances the blockade of an enemy fort by making it more difficult to smuggle in supplies.
Corduroy Road – logs laid side-by-side in a roadbed to make it passable in wet weather
Counterscarp - outer slope of a ditch. See scarp. Cut slightly at an angle to help deter erosion and sloughing, the counterscarp is visible in some condition in all ditches.
Covered Way – In permanent fortifications, a covered walkway extending around the outside of the moat or ditch of the main line. In fieldworks, a “covered way” generally refers to a parapet designed to protect and conceal the movement of troops and supplies. It may extend from camps or supply caches in the rear to service the fighting men in the front lines.
Cremaillière - an indented or zigzag line of fortifications. The intent was to allow musketry toward the front and across the front, creating crossfires in front of the line.
Cunette - a narrow drainage ditch running along the bottom of a trench.
Curtain or Curtain Wall - a line of fortifications connecting two bastions; a parapet connecting two batteries.
Defilade or Dead Ground- a depression within range of an earthwork's weapons that cannot be seen by defenders.
Demilune – a crescent shaped parapet protecting a single cannon, typically ditched in front. Also called an epaulement. In permanent fortifications, a component of the bastion.
Dentate – zigzag or toothed trace
Detached Works - fortifications constructed in front of the main line or as components of a discontinuous line, generally redans, lunettes, or redoubts. Also Advanced Works.
Discontinuous Line – a line of mutually supporting detached works, typically redans, lunettes, or redoubts, that are not connected by infantry parapets.
Ditch – excavation providing soil to construct a parapet. A ditch could be in front of the parapet (front ditch), behind it (back ditch), or on both sides. Engineers preferred front ditch construction whenever time and labor permitted, as the ditch provided an additional defensive obstacle. Batteries, redans, lunettes, and redoubts nearly always have a front ditch. Back ditch construction was preferred for rapid infantry entrenchments as this provided more protection, more quickly. Ditching on both sides was used to widen an existing parapet or to provide a covered way behind a front-ditched line. Some evidence of the ditch—a shallow trough—often survives even if its parapet has eroded away. The scarp and counterscarp are the inner and outer slopes of the ditch. Ditch and trench are often used interchangeably in the literature.
Earthworks -- any earthen structure excavated for military purposes. Earthworks constructed in anticipation of need, to defend a town, depot, or bridge, for example, were called deliberate, prepared, or provisional. The term fieldwork referred to any earthwork constructed by forces “in the field” on active campaign--whether on the battlefield or in camp. Fieldworks constructed spontaneously in the presence of the enemy and with ad hoc materials were called hasty entrenchments in the nineteenth century or rapid entrenchments in modern parlance. The term breastworks referred to a linear earthwork that was tall enough to cover the chest of a man standing behind it. Siegeworks were built to advance or inhibit operations against opposing fortifications and were often a mixture of deliberate and rapid earthworks.
Embrasure - a wedge-shaped opening cut to allow artillery to fire through the parapet. A cannon firing en embrasure had a restricted (45°) field of fire but the gunners were protected by the parapet. The sides or “cheeks” of an embrasure were reinforced by logs, planks, stones, sandbags, or gabions. Embrasures were common features of artillery fortifications and often survive as an indentation in the otherwise uniform parapet crest. Not all indentations are embrasures. Typically, there is other evidence of the presence of artillery—a gun platform and gun ramp, for example. A single gun might have had multiple embrasures. See barbette.
Enceinte (en-saint’) – area of a fort or redoubt enclosed by the parapet.
Enfilade – fire from the flank that sweeps along the length of a line.
Entanglement – obstacles placed in front of an earthwork to trip up and delay attackers. Sometimes, used as another name for abatis. Telegraph wire was sometimes strung from stump to stump at shin level to form a “wire entanglement.” As yet, no wire has been found to survive in the ground, having been retrieved or scavenged.
Entrenchment - generic term for any form of earthen fortification.
Epaulement – a crescent shaped parapet protecting a single cannon, typically ditched in front. Also called a demilune.
Exterior Slope – outer side of the parapet that faced the enemy. The exterior slope was usually constructed with an angle of about 45 degrees; the interior slope was more perpendicular to enable defenders to stand directly behind it. Nearly all extant earthworks will display some difference in angle between the exterior and interior slopes. See interior and superior slopes.
Face – a straight section of parapet making up a larger earthwork that delivers direct or oblique fire to the front.
Fascine – a tightly bound bundle of saplings used to reinforce a parapet or in revetment. Often used in conjuction with gabions. Archeological evidence of the use of fascines might appear as a darker strata of soil in the cross-section.
Field of Fire – area within weapons range that can be seen and swept by fire. Fields of Fire
Fieldwork or fieldworks – earthworks constructed by armies while actively campaigning.
Flank – segment of an earthwork positioned to protect the side of the position or to allow defenders to deliver a flanking fire. See enfilade.
Foxhole – an individual shelter hole. See rifle pit.
Fraise (frez) – a row of pointed logs placed close together and inclined toward the enemy. Sometimes called a palisade.
Front – toward the enemy.
Front-ditch or Exterior Ditch – ditch dug in front of a parapet as an additional obstacle to assault. A front-ditch allowed the parapet to have greater bulk and a stronger profile than rear-ditch construction. This was the engineers’ preferred method and was consistently applied to prepared fortifications, to detached works, and artillery fieldworks. See rear-ditch. It is common to find a mix of front- and rear-ditch entrenchments in a single continuous line.
Gabion - a large basket formed of interwoven vines and saplings that was first positioned then filled with earth on site. Gabions were used to reinforce a parapet, as revetment, or to shape embrasures. When gabions eroded, the fill collapsed into a shapeless mound. www.loc.gov/pictures/item/2012649823/
Glacis (glassis)– outer edge of the ditch, or, by extension, the field of fire of a fortification. In permanent fortifications, the glacis was shaped so that the ground rose gently as it approached the ditch to protect and conceal the masonry revetment of the scarp. In fieldworks, time permitting, the glacis was sloped as a continuation of the angle of the superior slope of the parapet. Some surviving artillery works have a shaped glacis, though it is fairly rare.
Gorge – entrance to a detached work, or simply the rear of the work, as in, a lunette is open “at the gorge.” A stockade was sometimes built to close off the gorge.
Grade – original ground level. Ditch is below grade; parapet is above grade.
Gun Pit – an entrenched artillery position, a demilune or epaulement.
Gun Platform – a flat, usually rectangular, area behind a parapet on which an artillery piece was positioned. The platform surface was usually covered by a plank or split log floor or “corduroyed” with logs placed side by side. A platform might be excavated or elevated relative to grade, depending on whether it was firing through an embrasure or over the parapet. The size of the platform is indicative of the size of cannon it was intended to service (average 14 x 18 ft. for a standard field piece). Sometimes, a platform was edged by a narrow drainage ditch, which may survive. The platform was sometimes flanked by traverses.
Gun Ramp – a ramp constructed to move a cannon into firing position on its platform. A gun ramp is a common surviving feature of artillery works.
Hasty Entrenchments – fieldworks constructed in the presence of the enemy. Also called Rapid Entrenchments.
Interior Slope – rear slope of the parapet, usually nearly vertical; often faced by a revetment of logs, rails, planks, sod, wickerwork (called hurdles), stones, sandbags, gabions, or other available materials.
Investment is the military process of surrounding an enemy fort or town with armed forces to prevent entry or escape. It serves both to cut communications with the outside world, and to prevent supplies and reinforcements from being introduced.
Keep – a blockhouse or earthwork, such as a redoubt, within a larger fort used as a place of final refuge or last-resort defense. Sometimes called a citadel or cavalier.
Loophole - an opening through which a weapon could be fired, while minimizing danger to the shooter. These could be improvised, as in an arrangement of sandbags, or prefabricated out of wood or metal and built into the parapet.
Lunette – a detached earthwork with two faces and two flanks and open to the rear; called a bastion when connected to other redans or lunettes by a curtain wall.
Magazine – a secure place to store ordnance supplies; in prepared works or fieldworks, a log or plank room or “bunker,” waterproofed and covered over with a thick layer of earth to protect ammunition from artillery fire. Most artillery fortifications that were occupied for any length of time had at least one magazine, depending on the number and types of guns. A surviving magazine typically appears as a large mound of earth, sometimes with a depression in the top where underlying timbers have collapsed or in the side where the entrance used to be. The entrance would be to the rear, opposite any incoming fire. Communication trenches or at least unobstructed paths for runners should lead from the entrance to the gun platforms. From visible remains, it is difficult to tell if a mound was a magazine or a bombproof. See Bombproof.
Military Crest – highest contour of an elevation from which the base of the slope can be seen.
Moat – ditch in front of an earthwork that was purposely filled with water.
Obstacles - were an essential component of fortifications that were designed to delay and hold attackers under fire. Obstacles might consist of a crude "slashing" of felled trees or, if time allowed, oa more organized abatis. Confederates were fond of chevaux-de-frise, which could be built in rear of the lines and transported to the front, while Federals preferred a fraise of parallel sharpened logs strongly laced together on-site. Telegraph wire strung between tree stumps was highly effective.
Palisade – a stockade; also, a phalanx of sharpened logs, anchored in a shallow ditch and slanted to the front as an obstacle to advancing infantry.
Parallel – a parapet thrown up to confront defenses when conducting a siege by “regular approaches.” The First Parallel was constructed out of range of the enemy’s guns. Saps were pushed forward fifty or a hundred yards to construct a Second Parallel, and so on, until reaching the ditch of the enemy fortification. See sap.
Parapet – a linear mound of earth built to defend against incoming fire. The thickness of a parapet was determined by the armament that it was expected to withstand—for musketry, 5-7 feet; field artillery, 11-18 feet; for siege or naval guns, up to 35 feet. The parapet consisted of an interior slope, usually revetted with logs, planks, rails, stones, or sandbags so as to be nearly perpendicular, the superior slope or crest, which inclined slightly downward toward the enemy, and the exterior slope or outer face, which sloped more steeply and bore the brunt of enemy fire. The exterior slope inclined 45 degrees, the natural angle of repose for most soils.
Picket or Skirmish Hole – slang for a one-man rifle pit, a foxhole.
Platform – see gun platform.
Prepared Entrenchments – works constructed in anticipation of need to defend towns, garrisons, depots or other fixed positions. Also called provisional or deliberate works.
Priest Cap - Two adjacent redans, placed side by side to form a fortification shaped like the letter M. Priest Cap
Ramp – an incline leading up to the banquette or allowing access to a gun platform.
Rampart – a broad embankment of earth that supports the functioning elements of a permanent or semi-permanent fortification. The parapet and banquette are built at the front for defense, while ramps are placed on the interior slope for movement of troops and equipment. In early forts, a rampart was often improvised by constructing double parallel revetments and filling the intervening space with hard-packed earth. Ramparts were not a typical component of field fortifications but may appear in simpler form in some artillery works.
Rapid Entrenchments – fieldworks constructed in the presence of the enemy. Also called hasty entrenchments.
Rear – away from the enemy.
Rear-ditch or Interior Ditch – ditch behind a parapet, commonly used in rapid infantry entrenchments. See front-ditch.
Redan – a detached fortification with two faces built as an outer work to cover an advanced position. The work is open at the gorge. A redan was a common form of all military eras. When separated by a traverse down its center (along the capital line), it was called a flLche.
Redoubt – an enclosed fortification, typically detached, that was designed to be defended from all sides. Redoubts were constructed in the shape of a square, polygon, or circle. At times, redoubts were constructed within larger fortifications or incorporated into long lines of entrenchments as strong points. Redoubts are a common feature of all military eras.
Reentering Angle or Reentrant- angle in an earthwork that points away from the enemy.
Regular Approaches - formal techniques of siege warfare, including sapping and tunneling.
Retrenchment – a secondary line of earthworks built to seal off a gap in the main line or to prevent a breakthrough.
Revetments – retaining wall constructed to support the interior slope of a parapet. Made of logs, wood planks, fence rails, fascines, gabions, sods or stones, the revetment provided additional protection from enemy fire, and, most importantly, kept the interior slope nearly vertical. Stone revetments commonly survive. A few log revetments have been preserved due to high resin pine or cypress and porous sandy soils.
Rifle Pit – a foxhole or a short trench providing cover for two or three men, though the term is imprecise. Often a hole four feet in diameter and three feet deep with the dirt thrown in front to form a low parapet. Rifle pits sheltered individuals on picket duty in advance of the main line or skirmishers. Many fine examples survive, but are easily confused with tree-throw. Look for a legible row of foxholes or slit trenches, separated by 5-12 yards.
Rifle Trench – a parapet for infantry, typically thrown up rapidly with a rear-ditch. The term was often used imprecisely.
Salient – a section of an line of works that protrudes outward toward the enemy.
Salient Angle – an angle in a work that points toward the enemy. See reentering angle.
Sally Port – opening left in the parapet as an entrance to an enclosed earthwork. All enclosed earthworks had a sally port; called a postern when vaulted over to form a tunnel.
Sandbag Loopholes -- sandbags stacked on top of a parapet to provide protection for a rifleman
Sap – a trench built to connect one parallel to the next in order to advance siegeworks. Sometimes built as a zigzag approach or with internal traverses. See parallel. July 1864 Map of Eighteenth Corps Lines
Sapper – a pioneer or engineer in charge of field or siegeworks.
Sap Roller - a large, gabion-like cylinder of woven reeds and saplings made to be musket-proof and used to advance a trench (sap) toward the enemy's line. www.loc.gov/pictures/item/2004660784/ www.loc.gov/pictures/item/2012649823/
Scarp – inner slope of the ditch. The counterscarp is the exterior slope.
Shelter Trench – a simple rifle trench for infantry, typically with a rear-ditch.
Sinks - latrines, typically a ditch topped by a log for sitting, resting on supports. Sinks were often dug in no-man's land as an obstacle. Civil War Sinks
Slit Trench – slang for a short trench, similar to a rifle pit, constructed for 3 - 5 men.
Star Fort – an enclosed work with salient and reentering angles but without bastions. A star fort might have from four to eight “points” projecting toward the enemy. This was a popular form until the middle of the Civil War, but many engineers considered it to require more work than needed for a strong defense. Examples of star forts survive from various time periods.
Stockade - A fortification where the wall is made of logs arranged vertically and tied together. Small loopholes were cut in the logs to allow for rifle fire. More popularly seen as defense from Indians, stockades were used as protection for the flanks and other points of fortifications where full earthworks were not deemed necessary. Also, stockades were built as defensive positions along roads, railroads, and river crossings. On occasion, a stockade would be employed as a strongpoint in a larger fort. Remains of a stockade are rare. It is possible that an archeologist may find evidence of the posthole or actual remains of the post in the ground. Often some use of an earthen structure employed in addition to the stockade. A banquette or a parapet wall may be present or a ditch in front where the dirt was thrown against the logs.
Terre-plein - A level space in the fortification. Usually identified as the area between the banquet and the interior slope of the rampart.
Traverse - Mounds of earth similar to a parapet that are constructed to cover entry points and areas vulnerable to enfilade fire. Often they were constructed within the fortification to provide cover if the enemy overran another portion of the fortification. Usually these structures were as massive as the main work and are as well preserve as the surrounding works.
Trench - The trench is usually three feet deep and from six to ten feet wide. A trench is the communication line, approach, zigzag, or parallel used by besiegers against fortifications. Often the word trench is used as slang to refer to the ditch of a fortification, or refer to the fortification itself.
Work - Loose term to refer to any component of the fortification or to the fortification as a whole.
Zigzag - defiled trenches used as parallels of attack while besieging fortifications. See trench.
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Angle - point where two straight faces of a fortification meet. Salient angles point toward the enemy; re-entering angles (reentrants) point away from the enemy.
Apex - foremost angle of a fortification.
Approach – a trench dug to get closer to the enemy line, called a sap in siege operations.
Banquette or Firing Step – a shelf dug behind a parapet that allowed a defender to step up from the ditch to fire over the parapet, then step back down under cover to reload. A banquette was only necessary when the parapet was higher than a man’s armpits. A common feature associated with prepared fortifications, its outline is often blurred or covered by earth eroding from the parapet.
Balk – a narrow barrier of earth within the ditch of an earthwork that was purposely left un-dug. Balks often show divisions between regiments in the line.
Barbette - artillery positioned to fire over the parapet rather than through an opening in it. (See embrasure). A cannon firing en barbette had an unrestricted (180°) field of fire, but the gunners were exposed to view. A cannon firing en embrasure had a restricted (45°) field of fire but the gunners were protected by the parapet. A barbette gun might be raised to fire over the parapet by means of a large carriage or by a gun platform built up to the appropriate height. See gun platform.
Bastion - a standard component of artillery fortifications into the twentieth century. A bastion was an angular work in the form of a lunette that projected outward from the main trace of the fortification. Its purpose was to eliminate dead ground by providing enfilade fire fronting an adjacent curtain. A bastion consisted of four parts: two salient faces oriented towards the enemy, and two reentering flanks that directed fire sideways across the faces of adjacent bastions. A curtain (or curtain wall) connected two or more bastions.
Bastioned Fort – an enclosed earthwork with bastions in the angles to provide fire along the fronts of the connecting parapets.
Battery - an artillery unit or a fortification designed to defend an artillery unit.
Berme or Berm – narrow ledge or shelf left at grade to separate the scarp of the ditch and the exterior slope of the parapet. When constructing large defenses, workers stood on the berm to heft earth up onto the parapet. The berm was often left to retard slumping of the parapet, but many engineers felt that it assisted attackers in scaling the parapet and had it pared down after construction. Soil eroding from the parapet will typically blur a berm’s outline.
Blockhouse - building constructed of heavy logs in the shape of a square, rectangle, or cross, to serve as a strong point for infantry or artillery. A ditch was often excavated around the exterior with the spoil thrown up against the wooden structure as a protection against fire and gunfire. Often part of the first floor of a blockhouse was below ground, while the upper floor, pierced with loopholes and embrasures, was built with an overhang so that defenders could fire down around the base of the structure. Blockhouses were used to defend railroad trestles, bridges, and depots, or served as a “keep” or place of final refuge in a larger fortress or stockade. The excavations associated with many blockhouses survive, although timbers were often scavenged for other uses. Some had brick or stone flooring and fireplaces.
Bombproof – a log or plank room or “bunker” covered over with earth to protect troops from artillery fire. A surviving bombproof appears as a large mound of earth, sometimes with a depression in the top where underlying timbers have collapsed or in the side where the entrance used to be. From visible remains, it is difficult to tell if a mound was a bombproof or a structure to store powder and ammunition. See magazine. A single mound within an artillery fortification is likely to have been a magazine, because powder was protected before men.
Boyau or Boyaux -- a communication trench.
Breaching Battery – a battery constructed during siege operations to enfilade a portion of the enemy’s defenses or to batter down the enemy’s walls or parapets.
Breastwork – usually a fieldwork no higher than a man’s chest. A breastwork could be constructed of earth, logs, stones, or whatever else might be at hand, such as cotton bales. The term is used very generically.
Capital – the imaginary line that bisects the salient angle of a work.
Cavalier – a portion of a fortification built higher and stronger than surrounding works to serve as a “keep” or place of final refuge.
Cheek - side of an embrasure. Often shaped by gabions or sandbags.
Caponière - a redan projecting from the front of a curtain wall to enable infantry or artillery to provide enfilade fire into the ditch.
Chevaux-de-frise – obstacles built of logs with projecting spikes, joined together by chains or ropes.
Circumvallation is a line of fortifications, built by the attackers around the beseiged fortification facing towards an enemy fort (to protect the besiegers from sorties by its defenders and to enhance the blockade. The resulting fortifications are known as 'lines of circumvallation'. Lines of circumvallation generally consist of earthen ramparts and entrenchments that encircle the besieged city or fortress. The line of circumvallation can be used as a base for launching assaults against the besieged city or for constructing further earthworks nearer to the city.
Communication Trench – a ditch and parapet that connect one part of an entrenchment with another to move troops and supplies. These were sometimes simple trenches, serving as arteries to direct reserves to some portion of the line. Called a covered way if deep enough to conceal movement.
Continuous Line – a line of fortifications presenting a solid front to the enemy. Parapets connect all of the artillery strong points on the line.
Contravallation may be constructed in cases where the besieging army is threatened by a field army allied to an enemy fort. This is a second line of fortifications outside the circumvallation, facing away from an enemy fort. The contravallation protects the besiegers from attacks by allies of the city's defenders and enhances the blockade of an enemy fort by making it more difficult to smuggle in supplies.
Corduroy Road – logs laid side-by-side in a roadbed to make it passable in wet weather
Counterscarp - outer slope of a ditch. See scarp. Cut slightly at an angle to help deter erosion and sloughing, the counterscarp is visible in some condition in all ditches.
Covered Way – In permanent fortifications, a covered walkway extending around the outside of the moat or ditch of the main line. In fieldworks, a “covered way” generally refers to a parapet designed to protect and conceal the movement of troops and supplies. It may extend from camps or supply caches in the rear to service the fighting men in the front lines.
Cremaillière - an indented or zigzag line of fortifications. The intent was to allow musketry toward the front and across the front, creating crossfires in front of the line.
Cunette - a narrow drainage ditch running along the bottom of a trench.
Curtain or Curtain Wall - a line of fortifications connecting two bastions; a parapet connecting two batteries.
Defilade or Dead Ground- a depression within range of an earthwork's weapons that cannot be seen by defenders.
Demilune – a crescent shaped parapet protecting a single cannon, typically ditched in front. Also called an epaulement. In permanent fortifications, a component of the bastion.
Dentate – zigzag or toothed trace
Detached Works - fortifications constructed in front of the main line or as components of a discontinuous line, generally redans, lunettes, or redoubts. Also Advanced Works.
Discontinuous Line – a line of mutually supporting detached works, typically redans, lunettes, or redoubts, that are not connected by infantry parapets.
Ditch – excavation providing soil to construct a parapet. A ditch could be in front of the parapet (front ditch), behind it (back ditch), or on both sides. Engineers preferred front ditch construction whenever time and labor permitted, as the ditch provided an additional defensive obstacle. Batteries, redans, lunettes, and redoubts nearly always have a front ditch. Back ditch construction was preferred for rapid infantry entrenchments as this provided more protection, more quickly. Ditching on both sides was used to widen an existing parapet or to provide a covered way behind a front-ditched line. Some evidence of the ditch—a shallow trough—often survives even if its parapet has eroded away. The scarp and counterscarp are the inner and outer slopes of the ditch. Ditch and trench are often used interchangeably in the literature.
Earthworks -- any earthen structure excavated for military purposes. Earthworks constructed in anticipation of need, to defend a town, depot, or bridge, for example, were called deliberate, prepared, or provisional. The term fieldwork referred to any earthwork constructed by forces “in the field” on active campaign--whether on the battlefield or in camp. Fieldworks constructed spontaneously in the presence of the enemy and with ad hoc materials were called hasty entrenchments in the nineteenth century or rapid entrenchments in modern parlance. The term breastworks referred to a linear earthwork that was tall enough to cover the chest of a man standing behind it. Siegeworks were built to advance or inhibit operations against opposing fortifications and were often a mixture of deliberate and rapid earthworks.
Embrasure - a wedge-shaped opening cut to allow artillery to fire through the parapet. A cannon firing en embrasure had a restricted (45°) field of fire but the gunners were protected by the parapet. The sides or “cheeks” of an embrasure were reinforced by logs, planks, stones, sandbags, or gabions. Embrasures were common features of artillery fortifications and often survive as an indentation in the otherwise uniform parapet crest. Not all indentations are embrasures. Typically, there is other evidence of the presence of artillery—a gun platform and gun ramp, for example. A single gun might have had multiple embrasures. See barbette.
Enceinte (en-saint’) – area of a fort or redoubt enclosed by the parapet.
Enfilade – fire from the flank that sweeps along the length of a line.
Entanglement – obstacles placed in front of an earthwork to trip up and delay attackers. Sometimes, used as another name for abatis. Telegraph wire was sometimes strung from stump to stump at shin level to form a “wire entanglement.” As yet, no wire has been found to survive in the ground, having been retrieved or scavenged.
Entrenchment - generic term for any form of earthen fortification.
Epaulement – a crescent shaped parapet protecting a single cannon, typically ditched in front. Also called a demilune.
Exterior Slope – outer side of the parapet that faced the enemy. The exterior slope was usually constructed with an angle of about 45 degrees; the interior slope was more perpendicular to enable defenders to stand directly behind it. Nearly all extant earthworks will display some difference in angle between the exterior and interior slopes. See interior and superior slopes.
Face – a straight section of parapet making up a larger earthwork that delivers direct or oblique fire to the front.
Fascine – a tightly bound bundle of saplings used to reinforce a parapet or in revetment. Often used in conjuction with gabions. Archeological evidence of the use of fascines might appear as a darker strata of soil in the cross-section.
Field of Fire – area within weapons range that can be seen and swept by fire. Fields of Fire
Fieldwork or fieldworks – earthworks constructed by armies while actively campaigning.
Flank – segment of an earthwork positioned to protect the side of the position or to allow defenders to deliver a flanking fire. See enfilade.
Foxhole – an individual shelter hole. See rifle pit.
Fraise (frez) – a row of pointed logs placed close together and inclined toward the enemy. Sometimes called a palisade.
Front – toward the enemy.
Front-ditch or Exterior Ditch – ditch dug in front of a parapet as an additional obstacle to assault. A front-ditch allowed the parapet to have greater bulk and a stronger profile than rear-ditch construction. This was the engineers’ preferred method and was consistently applied to prepared fortifications, to detached works, and artillery fieldworks. See rear-ditch. It is common to find a mix of front- and rear-ditch entrenchments in a single continuous line.
Gabion - a large basket formed of interwoven vines and saplings that was first positioned then filled with earth on site. Gabions were used to reinforce a parapet, as revetment, or to shape embrasures. When gabions eroded, the fill collapsed into a shapeless mound. www.loc.gov/pictures/item/2012649823/
Glacis (glassis)– outer edge of the ditch, or, by extension, the field of fire of a fortification. In permanent fortifications, the glacis was shaped so that the ground rose gently as it approached the ditch to protect and conceal the masonry revetment of the scarp. In fieldworks, time permitting, the glacis was sloped as a continuation of the angle of the superior slope of the parapet. Some surviving artillery works have a shaped glacis, though it is fairly rare.
Gorge – entrance to a detached work, or simply the rear of the work, as in, a lunette is open “at the gorge.” A stockade was sometimes built to close off the gorge.
Grade – original ground level. Ditch is below grade; parapet is above grade.
Gun Pit – an entrenched artillery position, a demilune or epaulement.
Gun Platform – a flat, usually rectangular, area behind a parapet on which an artillery piece was positioned. The platform surface was usually covered by a plank or split log floor or “corduroyed” with logs placed side by side. A platform might be excavated or elevated relative to grade, depending on whether it was firing through an embrasure or over the parapet. The size of the platform is indicative of the size of cannon it was intended to service (average 14 x 18 ft. for a standard field piece). Sometimes, a platform was edged by a narrow drainage ditch, which may survive. The platform was sometimes flanked by traverses.
Gun Ramp – a ramp constructed to move a cannon into firing position on its platform. A gun ramp is a common surviving feature of artillery works.
Hasty Entrenchments – fieldworks constructed in the presence of the enemy. Also called Rapid Entrenchments.
Interior Slope – rear slope of the parapet, usually nearly vertical; often faced by a revetment of logs, rails, planks, sod, wickerwork (called hurdles), stones, sandbags, gabions, or other available materials.
Investment is the military process of surrounding an enemy fort or town with armed forces to prevent entry or escape. It serves both to cut communications with the outside world, and to prevent supplies and reinforcements from being introduced.
Keep – a blockhouse or earthwork, such as a redoubt, within a larger fort used as a place of final refuge or last-resort defense. Sometimes called a citadel or cavalier.
Loophole - an opening through which a weapon could be fired, while minimizing danger to the shooter. These could be improvised, as in an arrangement of sandbags, or prefabricated out of wood or metal and built into the parapet.
Lunette – a detached earthwork with two faces and two flanks and open to the rear; called a bastion when connected to other redans or lunettes by a curtain wall.
Magazine – a secure place to store ordnance supplies; in prepared works or fieldworks, a log or plank room or “bunker,” waterproofed and covered over with a thick layer of earth to protect ammunition from artillery fire. Most artillery fortifications that were occupied for any length of time had at least one magazine, depending on the number and types of guns. A surviving magazine typically appears as a large mound of earth, sometimes with a depression in the top where underlying timbers have collapsed or in the side where the entrance used to be. The entrance would be to the rear, opposite any incoming fire. Communication trenches or at least unobstructed paths for runners should lead from the entrance to the gun platforms. From visible remains, it is difficult to tell if a mound was a magazine or a bombproof. See Bombproof.
Military Crest – highest contour of an elevation from which the base of the slope can be seen.
Moat – ditch in front of an earthwork that was purposely filled with water.
Obstacles - were an essential component of fortifications that were designed to delay and hold attackers under fire. Obstacles might consist of a crude "slashing" of felled trees or, if time allowed, oa more organized abatis. Confederates were fond of chevaux-de-frise, which could be built in rear of the lines and transported to the front, while Federals preferred a fraise of parallel sharpened logs strongly laced together on-site. Telegraph wire strung between tree stumps was highly effective.
Palisade – a stockade; also, a phalanx of sharpened logs, anchored in a shallow ditch and slanted to the front as an obstacle to advancing infantry.
Parallel – a parapet thrown up to confront defenses when conducting a siege by “regular approaches.” The First Parallel was constructed out of range of the enemy’s guns. Saps were pushed forward fifty or a hundred yards to construct a Second Parallel, and so on, until reaching the ditch of the enemy fortification. See sap.
Parapet – a linear mound of earth built to defend against incoming fire. The thickness of a parapet was determined by the armament that it was expected to withstand—for musketry, 5-7 feet; field artillery, 11-18 feet; for siege or naval guns, up to 35 feet. The parapet consisted of an interior slope, usually revetted with logs, planks, rails, stones, or sandbags so as to be nearly perpendicular, the superior slope or crest, which inclined slightly downward toward the enemy, and the exterior slope or outer face, which sloped more steeply and bore the brunt of enemy fire. The exterior slope inclined 45 degrees, the natural angle of repose for most soils.
Picket or Skirmish Hole – slang for a one-man rifle pit, a foxhole.
Platform – see gun platform.
Prepared Entrenchments – works constructed in anticipation of need to defend towns, garrisons, depots or other fixed positions. Also called provisional or deliberate works.
Priest Cap - Two adjacent redans, placed side by side to form a fortification shaped like the letter M. Priest Cap
Ramp – an incline leading up to the banquette or allowing access to a gun platform.
Rampart – a broad embankment of earth that supports the functioning elements of a permanent or semi-permanent fortification. The parapet and banquette are built at the front for defense, while ramps are placed on the interior slope for movement of troops and equipment. In early forts, a rampart was often improvised by constructing double parallel revetments and filling the intervening space with hard-packed earth. Ramparts were not a typical component of field fortifications but may appear in simpler form in some artillery works.
Rapid Entrenchments – fieldworks constructed in the presence of the enemy. Also called hasty entrenchments.
Rear – away from the enemy.
Rear-ditch or Interior Ditch – ditch behind a parapet, commonly used in rapid infantry entrenchments. See front-ditch.
Redan – a detached fortification with two faces built as an outer work to cover an advanced position. The work is open at the gorge. A redan was a common form of all military eras. When separated by a traverse down its center (along the capital line), it was called a flLche.
Redoubt – an enclosed fortification, typically detached, that was designed to be defended from all sides. Redoubts were constructed in the shape of a square, polygon, or circle. At times, redoubts were constructed within larger fortifications or incorporated into long lines of entrenchments as strong points. Redoubts are a common feature of all military eras.
Reentering Angle or Reentrant- angle in an earthwork that points away from the enemy.
Regular Approaches - formal techniques of siege warfare, including sapping and tunneling.
Retrenchment – a secondary line of earthworks built to seal off a gap in the main line or to prevent a breakthrough.
Revetments – retaining wall constructed to support the interior slope of a parapet. Made of logs, wood planks, fence rails, fascines, gabions, sods or stones, the revetment provided additional protection from enemy fire, and, most importantly, kept the interior slope nearly vertical. Stone revetments commonly survive. A few log revetments have been preserved due to high resin pine or cypress and porous sandy soils.
Rifle Pit – a foxhole or a short trench providing cover for two or three men, though the term is imprecise. Often a hole four feet in diameter and three feet deep with the dirt thrown in front to form a low parapet. Rifle pits sheltered individuals on picket duty in advance of the main line or skirmishers. Many fine examples survive, but are easily confused with tree-throw. Look for a legible row of foxholes or slit trenches, separated by 5-12 yards.
Rifle Trench – a parapet for infantry, typically thrown up rapidly with a rear-ditch. The term was often used imprecisely.
Salient – a section of an line of works that protrudes outward toward the enemy.
Salient Angle – an angle in a work that points toward the enemy. See reentering angle.
Sally Port – opening left in the parapet as an entrance to an enclosed earthwork. All enclosed earthworks had a sally port; called a postern when vaulted over to form a tunnel.
Sandbag Loopholes -- sandbags stacked on top of a parapet to provide protection for a rifleman
Sap – a trench built to connect one parallel to the next in order to advance siegeworks. Sometimes built as a zigzag approach or with internal traverses. See parallel. July 1864 Map of Eighteenth Corps Lines
Sapper – a pioneer or engineer in charge of field or siegeworks.
Sap Roller - a large, gabion-like cylinder of woven reeds and saplings made to be musket-proof and used to advance a trench (sap) toward the enemy's line. www.loc.gov/pictures/item/2004660784/ www.loc.gov/pictures/item/2012649823/
Scarp – inner slope of the ditch. The counterscarp is the exterior slope.
Shelter Trench – a simple rifle trench for infantry, typically with a rear-ditch.
Sinks - latrines, typically a ditch topped by a log for sitting, resting on supports. Sinks were often dug in no-man's land as an obstacle. Civil War Sinks
Slit Trench – slang for a short trench, similar to a rifle pit, constructed for 3 - 5 men.
Star Fort – an enclosed work with salient and reentering angles but without bastions. A star fort might have from four to eight “points” projecting toward the enemy. This was a popular form until the middle of the Civil War, but many engineers considered it to require more work than needed for a strong defense. Examples of star forts survive from various time periods.
Stockade - A fortification where the wall is made of logs arranged vertically and tied together. Small loopholes were cut in the logs to allow for rifle fire. More popularly seen as defense from Indians, stockades were used as protection for the flanks and other points of fortifications where full earthworks were not deemed necessary. Also, stockades were built as defensive positions along roads, railroads, and river crossings. On occasion, a stockade would be employed as a strongpoint in a larger fort. Remains of a stockade are rare. It is possible that an archeologist may find evidence of the posthole or actual remains of the post in the ground. Often some use of an earthen structure employed in addition to the stockade. A banquette or a parapet wall may be present or a ditch in front where the dirt was thrown against the logs.
Terre-plein - A level space in the fortification. Usually identified as the area between the banquet and the interior slope of the rampart.
Traverse - Mounds of earth similar to a parapet that are constructed to cover entry points and areas vulnerable to enfilade fire. Often they were constructed within the fortification to provide cover if the enemy overran another portion of the fortification. Usually these structures were as massive as the main work and are as well preserve as the surrounding works.
Trench - The trench is usually three feet deep and from six to ten feet wide. A trench is the communication line, approach, zigzag, or parallel used by besiegers against fortifications. Often the word trench is used as slang to refer to the ditch of a fortification, or refer to the fortification itself.
Work - Loose term to refer to any component of the fortification or to the fortification as a whole.
Zigzag - defiled trenches used as parallels of attack while besieging fortifications. See trench.
updated 02/25/2016
