Civil War Fortifications Tour
Museum of the Confederacy, April 5, 2003
“The great destruction of life, in open assaults, by columns exposed within so long a
range, must give additional value to entrenched fields of battle; and we may again see
fieldworks play the part they did in the defense of Sebastopol; and positions so chosen and
fortified that not only will the assailant be forced to entrench himself to assail the enemy,
but will find the varying phases of his attack met by corresponding changes in the
defensive dispositions.”
--Dennis Hart Mahan, West Point, 1863
Definition
A military earthwork is defined as any primarily earthen structure erected for a military purpose.
During the Civil War, earthworks were called intrenchments, trenches, rifle or shelter trenches, rifle
pits, parallels, earthen defenses, or breastworks, or just works—often interchangeably. Military
earthworks were an integral part of military operations from the beginning and throughout the war.
The veteran soldiers’ ability to rapidly construct shelter for themselves—learned during 1863 and
developed to a fine art in 1864—constituted a principal tactical innovation of the Civil War.
Types of Construction
The parapet is the protective mound of earth. The ditch is the excavation from which the dirt is
removed. A fill of logs, fence rails, or stones is piled up along the intended line before digging begins.
The revetment is a retaining wall of logs, planks, sandbags, or stones added to hold the earth vertical.
The illustration below left shows front (exterior) ditch construction, favored by engineers for both
artillery and infantry works when time permitted. The advantage is that the ditch (like a dry moat)
provided an additional layer of defense; the ditch can be deeper and the parapet fatter. The example
below right shows a typical “rifle trench” constructed rapidly in the field. The ditch was usually dug
deep enough so that a standing soldier could steady his weapon atop the parapet. The advantage of
rear (interior) ditch construction was speed—every scoop of earth simultaneously lowered the ditch
and raised the parapet. Sometimes, the soldiers would dig a rear-ditch work and later make the parapet
fatter by excavating a second front ditch (often when taking incoming artillery rounds!) A captured
line of earthworks could be “turned,” dug by the captors to face in the opposite direction.
Digging In
A unit deployed in formation along a line selected by the officers, typically along the military crest of
a local terrain feature, and began digging with bayonets and other makeshift tools, throwing the earth
toward the enemy. Working parties gathered fence rails, downed trees, or stones, and pile these
materials along the line, adding bulk to the growing parapet. When available, entrenching tools—
shovels, picks, and axes—were passed from unit to unit to deepen and improve the position. One pick
loosened enough earth to keep two shovels hard at work. In the woods, axe-men cut down trees and
brush in front of the line to open a clear field of fire. Within two or three hours, depending on soil
type and vegetation, an entire line could be entrenched to a relief of four feet, so that the parapet would
cover the chest of a soldier standing in the ditch.
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Military Earthworks Logic
The modern military uses an acronym—KOCOA—for analyzing the combat value of terrain and
for positioning troops on the battlefield. These letters stand for Key Terrain; Observation and
Field of Fire; Cover and Concealment; Obstacles; Avenues of Approach and Withdrawal. These
principles applied as much in 1864 to the siting of field fortifications as today. In 1864, General
Henry Hunt distilled four rules for siting artillery: 1) The efficacy of fire of the battery
(observation and field of fire); 2) Cover for the pieces from the enemy's fire (cover and
concealment); 3) The position of the rest of the troops (key terrain and mutual support); and 4)
Facility of movement (avenues of approach and withdrawal). Official Records, Serial 88, pp. 574575. Entrenchments enhanced the combat value of the terrain by seizing the military crest to
eliminate defilade (dead ground), which provided an extended field of fire and simultaneously
cover and concealment.
KOCOA
Classification is based on scale, time in preparation, and function. The large prepared-in-advance
fortification at far left (Class 1 or 2) dwarfs the rapid exterior-ditched infantry work center and the rearditched rifle trench at right (Class 4). Obstacles such a felled-trees, palisades, or entanglements were
typically placed 50-100 yards in front of the earthwork to delay and break up an attack.
Federal Soldiers in their Rifle Trenches along North Anna River (detail of impromptu sun shades)
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Earthworks Classification
(Adopted by the Civil War Fortifications Study Group at Nashville, 1999)
Class One: PREPARED ARTILLERY ENTRENCHMENTS
Includes forts, redoubts, bastions, lunettes, redans, batteries, blockhouses
Builders: laid out or renovated by engineers
Type of construction: "classic" prototypes, front-ditched, revetted
Materials: gabions (wicker baskets filled with soil),
sandbags, fascines (long, bound bundles of saplings),
log, plank, sod, stone revetments
Dimensions: 12-20+ feet relief, 15-25+ feet width of
parapet
Features: artillery platforms, embrasures, firing-steps,
additional interior works
Situation: semi-permanent defense of towns, depots,
transportation routes, river crossings, sieges; may be
improved from rapid entrenchments during prolonged
battle situation.
Class Two: PREPARED INFANTRY ENTRENCHMENTS
Includes siegeworks, main lines or breastworks, parallels,
connecting curtains, blockhouses
Builders: laid out or renovated by engineers
Type of construction: typically front-ditched, revetted
Materials: log, plank, sod, stone revetments
Dimensions: 6-15 feet relief, 12-25 feet width of parapet
Features: firing-steps, traverses, individual shelter pits
Situation: semi-permanent defense of towns, depots, transportation routes, river crossings,
sieges; may be improved from rapid entrenchments during prolonged battle situation.
Class Three: RAPID ARTILLERY ENTRENCHMENTS
Includes breastworks, minor artillery "lunettes" or demi-lunes
Builders: typically laid by field officers for their units, thrown
up quickly, often under fire
Type of construction: front-ditched, rear-ditched, ditch-both
sides, revetted or not
Materials: materials at hand - piled stone, fence rail, or log fill
- log, sapling, fence rail, wicker, stone revetment
Dimensions: 3-6 feet relief, 12-15 feet width of parapet
Features: artillery platforms, traverses, holes for ammo
chests
Situation: battlefield, bivouac, defense of roads, railroads, river crossings
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Class Four: RAPID INFANTRY ENTRENCHMENTS
Includes breastworks, rifle trenches
Builders: typically laid out by field officers for their
units, thrown up quickly, often under fire
Type of construction: front-ditched, rear-ditched,
ditch-both sides, revetted or not
Materials: materials at hand - piled stone, fence
rail, or log fill - log, sapling, fence rail, wicker, stone revetment
Dimensions: 2-5 feet relief, 8-15 feet width of parapet
Features: bays, balks, traverses, "command" holes
Situation: battlefield, bivouac, defense of roads, railroads, river crossings
Class Five: COMMUNICATION AND SUPPLY
Includes communication trenches, covered ways, entrenched military
roads, “zigzag trenches”
Builders: laid out by engineers or field officers
Type of construction: front-ditched, rear-ditched, ditch-both sides,
parapet both sides, revetted or not
Materials: earth, log, stone or wicker revetment
Dimensions: ditch 3-15 feet wide
Features: associated holes and bunkers for storage
Situation: semi-permanent fortifications, siegeworks, or prolonged battle when front line
troops need resupply
Class Six: INTERNAL WORKS
Includes magazines, bombproofs, bunkers, traverses associated with enclosed or semienclosed artillery fortifications
Builders: laid out by engineers to strengthen prepared
positions
Type of construction: square or rectangular hole with
surrounding berm, sometimes roofed; internal parapet
designed to provide defilade
Materials: earth, plank or log sides, flooring, sometimes roofed, sandbags, gabions
Dimensions: 5-15+ feet per side; traverses of varying length, relief
Features: Access door or trench
Situation: Associated with prepared artillery positions, siegeworks
Class Seven: PERSONAL FIELD SHELTER
Includes: discrete fox holes, picket or skirmish holes,
command holes, slit trenches, "rifle pits"
Builders: typically sited by individuals in action
Type of construction: hole with earth thrown to front or
shallow trench, rear-ditched
Materials: earth, sometimes wood or stone fill, typically not
revetted
Dimensions: 2-5 feet relief, 2-8 feet width of parapet
Features: discontinuous, arrayed in pattern of unit, shelters 1-3 persons, slit trenches shelter
4-10 persons
Situation: picket or skirmish lines, holes associated with rapid entrenchments
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Class Eight: DEFENSES OF CONVENIENCE
Includes: stone walls, piled stone breastworks, sunken roads, railroad
cuts/fills, often enhanced by digging
Builders: pre-existing features adapted to combat or constructed ad hoc
by soldiers
Type of construction: various
Materials: stone, wood, earth
Dimensions: various
Features: walls, barricades
Situation: meeting battles, stony ground, shallow topsoil
Further Reading
Christopher Duffy, Fire and Stone: The Science of Fortress Warfare 1660-1860. London: David and
Charles, 1975.
Paddy Griffith, Battle Tactics of the Civil War. New Haven: Yale University Press, 1989.
Edward Hagerman, The American Civil War and the Origins of Modern Warfare. Bloomington: Indiana
University Press, 1988.
O. E. Hunt, "Entrenchments and Fortifications," in Francis Trevelyan Miller, ed., The Photographic
History of the Civil War, vol 5, 194-218.
W. C, Johnson and E.S. Hartshorn. "The Development of Field Fortifications in the Civil War" in
Professional Memoirs, Corps of Engineers, United States Army and Engineer Department at
Large, 7, September-October 1915, 570-602.
Robert K. Krick, "Fire and Stone." In Touched by Fire: A Photographic Portrait of the Civil War. Edited
by William C. Davis. Boston: Little, Brown, 1986, Volume 2, 111-58.
David W. Lowe, “Field Fortifications in the Civil War” in North and South Magazine 4, no. 6 (Summer
2001).
Dennis Hart Mahan, A Summary of the Course of Permanent Fortification and the Attack and Defense
of Permanent Works. Richmond: West and Johnston, 1863.
Dennis Hart Mahan, Treatise on Field Fortification, Containing Instructions on the methods of laying
out, constructing, defending, and attacking Intrenchments, with the General Outlines also of the
Arrangement, the Attack, and the Defense of Permanent Fortifications. New York: John Wiley,
1863.
James St. Clair Morton, Memoir of American Fortification. Washington: 1859.
Noah Andre Trudeau, "The Walls of 1864: Field Entrenchments Saved Robert E. Lee's Army--and
Grant's as Well." MHQ: The Quarterly Journal of Military History, 6, Winter 1994, 23-31.
Arthur L. Wagner, “Hasty Entrenchments in the War of Secession” in Journal of the Military Service
Institution of the United States, 22, February 1898, 225-46.
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Detail showing fortifications at Cold Harbor in the vicinity of the National Park Cold Harbor Unit. From
Michler map series (8” = 1 mile), NARA Record Group 77 G204-33 through G204-60. The topographical
engineers depicted principal features but were unable to portray the complexity found on the ground.
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