Sally port, parapet wall and ditch visible at Fort Stedman , Petersburg National Battlefield, photoby Jon Buono.
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Military Earthworks Terms
Ramp - an incline leading up to the banquette
or allowing access to a gun platform.
Rampart - a broad embankment of earth that supported
the functioning elements of a permanent or semi-permanent fortification.
The parapet and banquette were built at the front of the rampart; ramps
moved troops from the interior of the work onto the terreplein
of the rampart. In early forts, a rampart was often improvised by constructing
double parallel revetments of logs and filling the intervening space with
stones and hard-packed earth. Ramparts typically were not a component
of field fortifications but appeared occasionally in simpler form in some
artillery works. Sometimes called a bulwark.
Rapid Entrenchments - fieldworks constructed in the
presence of the enemy, usually with a rear or interior ditch and often
with ad hoc materials for fill and revetment, also called hasty or temporary
entrenchments. Although built "hastily, " these were rarely built "carelessly,"
as the modern use of the word might imply. Experienced soldiers could
throw up a shelter trench sufficient to absorb small arms fire in less
than an hour with only rudimentary tools.
Ravelin - a detached earthwork open to the rear with
two long faces forming a salient angle and two short flanks.
See Detached Works.
Rear - interior, away from the enemy.
Rear-ditch or Interior Ditch - ditch
in which soldiers stood to fire over the parapet; most commonly used in
rapid infantry entrenchments. Rear-ditch was the fastest way to entrench
because each shovel of earth lowered the ditch and at the same time raised
the parapet. See Ditch.
Redan (Fr.) - a detached fortification with two faces
forming a salient angle, often built as an outer work to cover
an advanced position. The work was open at the rear. A redan was a common
form of all military eras. When bisected by a traverse down its center
(along the capital line), it was called a flêche, or "arrow."
When connected to adjacent strong points by curtain walls, it served as
Redan Line - a series of redans connected by
Redoubt - an enclosed fortification designed to be defended
from all sides. The trace of a redoubt could be square, polygonal,
or occasionally circular. A redoubt could stand alone as a detached
work, serve as a place of refuge within a larger fortification, or
be incorporated into a continuous line of entrenchments as an artillery
or infantry strong point. Redoubts were a common feature of all
Reentering Angle or Reentrant - angle in an earthwork
or line of earthworks that points toward the rear and away from the enemy.
Systems of earthworks were purposely designed with both reentering and
Reface - to "turn" or change the facing of an
Relief - distance from the crest of the parapet to the
bottom of the ditch; relief is a component of the profile.
Regular Approaches - siege operations conducted by building
saps, parallels, and breaching batteries, based largely on a system devised
for the French armies by Sebastien le Prestre de Vauban (1633-1707).
Regular and Irregular Works - enclosed earthworks.
Regular works were based on classic models-square or six-sided redoubts,
and bastioned forts-and generally appeared balanced in proportion and
symmetrical in trace. Irregular works were adapted to the peculiarities
of the terrain and took a variety of shapes and traces. Although less
"elegant" in terms of geometry, irregular works were often measurably
stronger than the more rigid, classical prototypes.
Remblai - See Spoil.
Retrenchment - a secondary line of earthworks built
to seal off a gap in the main line or to prevent a breakthrough.
Reversed Fire - incoming fire that strikes the rear
of a parapet or line of battle. Incoming fire could be direct, enfilading,
oblique, plunging, reversed, and ricochet.
Revetment - retaining wall constructed to support the
interior slope of a parapet. Made of logs, wood planks, fence rails,
fascines, gabions, hurdles, 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. After an entrenchment was abandoned, many log or rail revetments
were scavenged for other uses, causing the interior slope to slump more
quickly. An interior slope will appear more vertical if the parapet eroded
with the revetment still in place.
Ricochet Fire - fire that strikes the ground first then
bounds into the air, used primarily by artillery firing a round, solid
shot. The glacis was shaped to deflect ricochet rounds up and
over the parapet rather than into it.
Rifle Pits - generically, any grouping of light, rapid
entrenchments, usually discontinuous, with a rear-ditch and low parapet.
See Holes and Pits.
Rifle Trench - a parapet for infantry, typically thrown
up rapidly with a rear-ditch. Also called a shelter trench.
Salient - a portion of a system of earthworks that protruded
or bulged outward toward the enemy.
Salient Angle - an angle in a work or line of earthworks
that pointed toward the enemy. See Reentering Angle. Systems
of earthworks were designed purposely with both reentering and salient
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 or roofed to form a tunnel.
Sandbags - used to strengthen prepared entrenchments
and siegeworks, often filled off-site and transported to the work under
construction. A stratum of sand overlying a different base soil, particularly
in an artillery work, might indicate the use of sandbags.
Sap - a trench built to connect one parallel to the
next in order to advance siegeworks, sometimes built as a zigzag approach
or straight with internal traverses. See Regular Approaches.
Sap Roller - a large wickerwork cylinder rolled ahead
of a crew to absorb incoming fire as it worked on a sap.
Sapper - a pioneer or engineer engaged in digging field
Scarp, Escarp, or Escarpment - inner slope of the ditch,
as opposed to counterscarp, the outer slope of a ditch. Both scarp
and counterscarp are below grade and are visible components of all ditches.
Sector Without Fire - area in front of a salient
angle into which the defenders cannot fire. A sector without fire
was extremely vulnerable unless defended by fire directed from another
part of the fortification.
Shelter Trench - a simple rifle trench for infantry,
typically with a rear-ditch.
Siege Operations - systematic entrenching to approach
an enemy's defenses, using classic engineering techniques. See Regular
Siegeworks - earthworks built to advance or retard siege
Skirmish Line - soldiers deployed at intervals in front
of the main line of battle to harass the enemy and delay any enemy advance;
a row of individual foxholes entrenched by the skirmishers. Skirmish
lines were advanced anywhere from 50-300 yards in front of the main lines,
depending on the terrain and proximity of the enemy. Sharpshooters often
manned the skirmish line.
Skirmish Pits or Picket Holes - See
Holes and Pits.
Slashing - cutting down all trees in front of a line
to create a clear field of fire. Trees were felled in the same direction
with branches toward the enemy, serving as an obstacle to attack. Downed
trees might then be trimmed and arranged more formally into an abattis.
Slit Trench - slang for a short trench, similar to a
rifle pit, constructed for 3-5 men. Often found in a picket line interspersed
with foxholes or as shelter in the rear of a main line.
Spoil - earth removed from an excavation, termed in
French the déblai. The spoil provided the bulk of the remblai,
that is, the material used to construct a rampart or parapet.
Star Fort - an enclosed work with alternating salient
and reentering angles. A star fort might have from four
to eight salient angles 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 - generically, a log fort; when used as an
adjunct to earthworks, a vertical wall of logs tied or nailed together
to protect the flank or gorge of a battery, lunette, or
redoubt. Loopholes were cut in the logs to allow for rifle fire. The
exterior of the stockade wall might be ditched with the earth thrown up
against the logs. Archeological excavation might reveal evidence of the
postholes or remains of the post in the ground.
Strong Point - a dominating position, usually high ground,
defended by entrenched artillery or a concentration of infantrymen; an
artillery work within a continuous line of entrenchments.
Superior Slope - crest of the parapet on which soldiers rested their
weapons to fire. The interior slope was nearly vertical
so that a man could stand comfortably against it. The superior slope
inclined slightly toward the enemy. The exterior slope, which
intercepted most incoming fire, inclined more abruptly. See Parapet.
Supply Cache - a rectangular excavation, usually 5-10
feet on a side and three feet deep, found in rear of the Main Line of
Defense. See Earthworks Complex. These served as temporary storage
for boxes of food or ammunition and are found in sheltered terrain adjacent
to a road or a covered way. On rare occasions in the field or during
siege operations, a supply cached might be roofed or partially roofed
with logs and earth.
Swallow's Tail - a detached earthwork consisting of
two faces joined in a reentrant and two long flanks extending
toward the rear and inclining toward the open gorge.
Tenaille (Fr.) Line - a series of adjacent redans,
of equal or differing sizes, joined at the flanks with no connecting curtains.
Terreplein (Fr.) - ground level, grade; generically
a level area inside an enclosed fortification; in permanent fortifications,
the flat surface of the rampart behind the parapet.
Tête-de-pont (Fr.) - an entrenched bridgehead with both
flanks anchored on a river, designed to hold a river crossing.
Throw Up Works - to entrench. Earthworks were described
as being "thrown up."
Trace - outline of a fortification as drawn on a plan
or "traced" upon the ground. In terms of engineering, the trace of an
earthwork was its most important characteristic. To be effective, the
trace should take advantage of the military strengths of the terrain and
mitigate its weaknesses; its design should accomplish its purpose in the
overall plan of defense; its length should be adjusted to the number of
soldiers designated to hold the position.
Traverse - a short segment of parapet used to prevent
incoming enfilade fire from sweeping the length of a line, to protect
the rear wall of an enclosed work from a plunging fire from the
front, to cover a sally port, or to provide extra protection for a magazine
or supply cache. Traverses were sometimes built of or reinforced by gabions
and were usually constructed perpendicular to incoming fire, rather than
perpendicular to the defensive parapet. In rapid entrenchments, traverses
might be constructed entirely of logs.
Trench - usually short for entrenchment, sometimes referring
to the ditch of an entrenchment or to an auxiliary entrenchment in rear
of a rampart.
Trous de loup (Fr.) - rows of pitfalls, 4-6 feet deep,
dug in checkerboard fashion in front of an earthwork to obstruct to an
attacking force. Each cone-shaped pitfall concealed a sharpened stake.
Turned Works - an entrenchment captured by the enemy
and refaced, resulting in ditching on both sides of the parapet.
Work - any discrete component of a system of fortifications,
applied most often to detached defenses, to forts, or artillery strong
Zigzag Trench - See Boyau.
Zone of Contention - No Man's Land, the area separating
the deployed skirmishers of the combatants, often defined by the foxholes
of the opposing skirmish lines. Because skirmishers tended to advance
or withdraw according to nuances of the terrain and localized pressure,
the width of this zone fluctuated. See Earthworks Complex.
Zone of Fire or Kill Zone - area between
the Main Line of Defense and the advanced skirmish or picket line,
typically no wider than the effective ranges of standard infantry weapons.
In this zone, soldiers cut down trees to clear a field of fire and often
erected obstacles, such as an abattis or entanglements, to slow
down and break up an attack. Nothing would remain from such obstructions
unless it was the shallow ditch that anchored the abattis. One might
find larger dugouts that held reserve pickets that could be fed out to
the skirmish line as needed. See Earthworks Complex.
Zone of Occupation - area behind the Main Line of Defense.
This zone might extend 200 yards or more behind the front, depending on
the terrain. In this zone were activities of logistics and support,
which sometimes left evidence in the form of support trenches, dug-out
supply caches, bunkers for officers and non-combatants, or covered ways
through which troops and supplies could move unseen from the rear to the
front line. In some cases, artillery positions were constructed to fire
over the front lines at distant targets. See Earthworks Complex.
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