Plan

Scale of

Redans

A redan was a simple field work consisting of two faces joined to form a salient, or outward projecting angle, in a line of defense works. Redans were used in conjunction with larger works as advanced posts to protect ground that could not otherwise be seen. In many cases, two or more redans were joined together to form double or triple redans, as in the Confederate lines at Fort Blakeley in Alabama. Fifty-five redans had been built into the Petersburg defenses by 1864. This type of field work could also be used to cover small posts guarding roads or bridges, provided the avenues of approach were restricted and the direction of enemy approach could be adequately predicted.

Lunettes

In field fortification, a lunette was a detached field work consisting of two faces, forming a salient angle, and two parallel flanks. Similar to redans, lunettes were employed as advanced works in front of a line with gaps. Lunettes were placed in the defenses of Washington DC in 1861. They were also used in the design of Fortress Rosecrans, an earthen fort constructed near Murfreesboro, Tennessee, after the Battle of Stones River, fought between December 31, 1862 and January 2, 1863. Large irregular lunettes were used to fortify the perimeter of the entrenched camp.

Entrenched Fortification Design
This blockhouse near the Aqueduct Bridge at Arlington Heights, Virginia, has an overhanging upper story, and an entrance reached by a freestanding staircase. (Library of Congress B8171-2282)

Blockhouses

Large field works often contained blockhouses, which were enclosed wooden fortifications that served as interior keeps. They also allowed small garrisons posted at isolated locations to protect themselves from attack by superior enemy forces. Blockhouse designs varied from simple single-level squares to large, two-storied, cross- or hexagon-shaped works capable of housing artillery. Logs at least 12 inches thick when squared on either two or four sides were considered the minimum material necessary for both walls and roofs to prevent penetration with common musket balls. Blockhouse walls were formed either by placing the logs upright and side by side, as in palisades, or they could be laid horizontally on top of each other and joined with notches in the manner of a common log cabin. The logs composing a vertical wall had to be buried at least three feet into the ground or set into a ground-sill, and their tops had to be mortised into a cap-sill, or head piece, to keep them from spreading and separating. Blockhouse walls were often banked up with earth to the loopholes, or surrounded by earthworks, which provided a partial mask from artillery fire.

To enable troops forming the garrison to work their ramrods without excess interference, nine feet was considered the minimum height necessary for a Civil War blockhouse wall. The minimum length was 12 feet, since a shorter wall would not provide space for enough loopholes to allow an adequate defense.

Bastions

Designed to project outward from the main enclosure of a fortification, bastions consisted of two faces and two flanks, and were so constructed that it was possible to defend by a flanking fire the adjacent curtain, or wall, which extended from one bastion to another. Two adjacent bastions were connected by a curtain wall, which joined the flank of one with the adjacent flank of the other.

Fortress Rosecrans

Fortress Rosecrans was the largest field fortification built during the Civil War. It was designed by General James St. C. Morton, who had taught engineering at West Point, and named for General William S. Rosecrans. It consisted of a line of detached lunettes and connecting works with intervals that would have allowed the defending force to counter-attack out of the camp. Constructed southeast of Nashville,Tennessee in early 1863 by Union troops occupying Murfreesboro following the Battle of Stones River, this massive earthen fortification served as a 200-acre base of occupation, and as a depot to supply troops as they marched to Atlanta. Its four redoubts, plus lunettes Thomas and McCook, contained cross-shaped blockhouses. With the exception of outworks Lunette Davis and Redan Van Cleve, all 14,000 feet of earthworks were linked together by either abatis or natural features such as the river. Much of this fortress was built by a 10 Pioneer Corps of specially selected, skilled men.

A reconstruction of the cross-shaped blockhouse in Redoubt Johnson is shown on the right. According to Mahan's principles of fortification, the ceiling height was to be not less than nine feet from ground level, to allow "ample room for loading the musket." The internal "camp beds of boards" on each side of the interior also served as raised firing platforms. Loopholes were placed at intervals of three feet along the walls, and vents were placed above each loophole to prevent the build up of powder smoke.The wooden doors, also containing loopholes, were protected by galleries.The whole structure was protected by a 12-foot-deep ditch, with a palisade standing at the foot of the outer slope, inside which was an infantry parapet.A removable bridge-way provided access across the ditch.The interior of the blockhouse is shown empty here, but would have been filled with knapsacks, cartridge boxes, gun racks, provisions, and other accoutrements of daily life, stacked up on shelves.

Mine Creek Battlefield

M Redoubt Schofield

2 Redoubt Brannan

3 Redoubt T.J.Wood

4 Redoubt Johnson

5 Lunette Negley

6 Lunette Stanley

7 Lunette Reynolds

8 Lunette Rousseau

9 Lunette Granger

10 Lunette Crittenden

I I Lunette McCook

12 Lunette Thomas

I 3 Lunette Palmer

14 Demi-lunette Davis

15 Demi-lunette Garfield

16 Battery Cruft

17 Battery Mitchell

Curtain wall I Curtain wall 2 Redan Van Cleve Quartermaster depot Ordnance depot Magazine

Commissary depot Saw mills

Rousseau Battery Racks
3?i<f. 52.
Roof Girder Plan

This plan and elevation of a blockhouse of single thickness, and showing the entrance protected by a gallery, was published in Mahan's An Elementary Course of Military Engineering in 1865. (Author's collection)

Any walls longer than 16 feet required girder and shore support framing to carry the weight of the roof. The maximum length was 24 feet, beyond which the wall would not support the weight of the roof, which had to be as thick as the walls.

Loopholes were cut at three-foot intervals along each wall and at least six feet above ground level to prevent an enemy from using them to fire into the blockhouse. These loopholes were wider on the interior side of the wall to allow muskets to be pointed in all directions, and narrow on the exterior side to offer as much protection as possible.

Blockhouses built to guard railroads and bridges were usually constructed with roofs and walls of double thickness in an effort to withstand artillery fire, using logs 18 inches in diameter and hewn to a face of eight inches where they made contact. Known as "American" or double-cased blockhouses, the inner logs were usually placed upright, while the outer ones were horizontal. A space was left in the outer casing sufficient for the garrison to fire from the loopholes made through the inner wall. The horizontal logs above the loopholes were supported by short uprights, mortised into them and into those just below.

The roof of most blockhouses was made to sustain the same external impact as the walls. This could consist of 12-inch square logs covered by a simple pitched roof to help the building shed water. Those built to the "American" system had pitched roofs filled with earth, three feet thick at the ridge and sloping towards the eaves to about six or nine inches, where it was confined by a pole plate. The earth was protected from the weather by board roofing. Tin or sheet-iron ventilators were inserted through the roof and ceiling, and a brick flue was built to receive the pipe of the stove used in cold weather.

Two-story blockhouses usually only had a light framework forming the ceiling of the lower level, while a resistant roof covered the upper level. The upper level could be constructed to project beyond all four walls of the lower section, or could be built at an angle to the lower level with just the four corners projecting. Those sections of the upper-level floor projecting beyond the lower level would be reinforced, and would contain loopholes and/or machicolations in the floor to allow troops to fire down on the heads of an enemy attempting to shelter along the lower-level walls.

The doorway was the weakest point on the blockhouse, and special precautions were taken to prevent the enemy from gaining direct and unimpeded access to the door. Two-level blockhouses usually had the door on the upper floor, reached by a freestanding staircase about six feet from the exterior wall, which had loose planks laid across to the doorway. If the enemy captured the staircase, the planks could be quickly pulled inside the blockhouse. This method had the great disadvantage of trapping the garrison inside the work, which was an unpleasant situation if the enemy succeeded in setting the blockhouse on fire! A better method of protecting the doorway was to construct a narrow gallery that opened on one end of the wall and turned to the right or left before it reached the doorway. This prevented enemy fire from reaching the door, while the attackers could only rush the door in single file under fire from the loopholes.

Fortifications

Gunners of the 4th New York Heavy Artillery loading a 24-pounder siege gun mounted on a wooden barbette carriage at Fort Corcoran,Virginia, in 1862. (Library of Congress B81 I - 2341)

Parapets

With regard to the defense of the parapet, the defending troops used the slope of the banquette as a ramp to mount the tread of the banquette, where they stood or leaned against the interior slope to fire across the superior slope. As the exterior slope absorbed most of the enemy fire, it was supported by the berme that prevented it from collapsing into the ditch. The scarp was the wall of the ditch closest to the parapet, so it had to be given a slope that would support the weight of the parapet. The bottom of the ditch was usually flat and often contained obstacles such as palisades and stockades. The counterscarp was the outer wall of the ditch. This was given a sharper grade than the scarp since it only had to support the weight of the glacis, which was a cleared ramp that forced attacking troops to run uphill and into fire delivered from the parapet.

Gunners of the 4th New York Heavy Artillery loading a 24-pounder siege gun mounted on a wooden barbette carriage at Fort Corcoran,Virginia, in 1862. (Library of Congress B81 I - 2341)

Fortifications

Artillery emplacements

Provided it was well placed, and its interior arrangements were properly constructed, artillery was a powerful accessory to the defense of a field work. Cannon could be mounted in a field work either on a barbette carriage, to fire over the parapet, or behind embrasures to fire through openings in the parapet. Barbette mountings allowed a wider field of fire, but exposed both gun and crew to enemy fire. Although embrasures allowed guns to be served from behind the protection of the parapet, they restricted fields of fire. There were also weak points in the parapet where attacking troops could enter a work under cover of the cheeks of the embrasures.

Artillery could be placed at any point along a parapet of a field work, where its fire could reach across the crest of the counterscarp. Howrever, it was best placed at salient angles, which jutted out from the main line, in order to reduce the number and extent of sectors without fire in front of the work. It was also best placed on flanking faces where its fire could be extended parallel to another face to catch attacking troops in a cross fire. Since

Soil compacted over a stout wooden frame has been supplemented with gabions and sandbags in this bomb-proof at Fort Sedgwick in the Federal lines during the siege of Petersburg, 1864-65. (Library of Congress B8171-3199)

This drawing by Alfred R.Waud shows a Confederate battery behind an earthwork with embrasures near Munson's Hill, Virginia, in September 1861. (Library of Congress USZ62-83034)

cannon mounted in field works would be required to fire repeatedly from the same spot, their weight had to be supported by a platform that would prevent them from sinking into soft soil and creating ruts when they recoiled.

Platforms for light field pieces could be as simple as three planks laid on the ground to support the wheels and trail. Mortars and heavy artillery mounted on siege carriages required more substantial platforms consisting of 12 sleepers laid in two rows, the second overlapping and at an angle to the first row. Thirty-six planks measuring 5 by 3]A inches were laid on the sleepers and fastened with dowels. A headpiece, called a "hurter," was placed at the front of the platform to prevent the wheels of the artillery carriage from striking the revetment of the interior slope. The hurter also permitted the piece to be run up to the embrasure and fired in the proper direction at night.

Bomb-proofs

Fortifications exposed to enemy shellfire often included bomb-proofs and shelters where troops occupying a work could retire when under enemy bombardment. Bomb-proofing in field fortifications generally required a heavy post and beam framework sunken below the natural level of the ground with a roof covering consisting of one or more courses of large-diameter timbers covered by four to six feet of tamped soil. Sometimes the dirt covering of a bomb-proof was pierced with loopholes from which rifleman could fire. Powder magazines were also made bomb-proof, and were sometimes included in parados traverses. Covered ways often linked bomb-proofs to the parapets to protect men on duty from enemy mortar shells, artillery fire, and sharpshooters.

Fort Negley (Harker)

A complex structure designed by General James St. Clair Morton, Fort Negley (later renamed Fort Harker) was 600 feet long, 300 feet wide, and covered four acres.The east (I) and west (2) parapets were partially star-shaped. Placed at the southern end of the fort, where attack was most likely, were two massive bomb-proof bastions (3 and 4) equipped with guns that could be aimed in several directions. Each bastion had tunnels that protected men moving through the works.The stone foundation of the fort was covered with dirt, which was designed to absorb the concussion of incoming artillery rounds and prevent the stonework from shattering. Grass was grown on the earthworks to prevent erosion. At the center of the fort was a 12-foot-high stockade (5) built of cedar posts, with a sentry box, or guerlte, above each corner. Underground water cisterns were placed inside the stockade, which was designed as the last defensive position in case the fort was overrun.Two tall trees left standing inside the fort near the stockade were intended for use as observation platforms and signal stations.Two ravelins (6 and 7) flanked the stockade. A gun emplacement fortified with railroad iron, called casement No. I,and containing a 30-pound Parrot rifle capable of hurling a 29-pound shell two and a half miles, was placed to the west of the stockade (8).Two more 24-pounders (9 and 10) were placed in casemates of timber in the South Main Work, "covered on the slope toward the enemy with railroad iron and made bomb-proof with earth." The other four guns in the fort were placed en barbette on wooden artillery platforms situated behind the east and west parapets (I I-14). Fort Negley was completed on December 7, 1862; it was never attacked.

FortificationsFortifications

Captured from the Confederates in September 1864, Battery or Fort Harrison, at Chaffin's Farm, in the Richmond defenses, was re-named Fort Burnham in honor of Federal General Hiram Burnham who was killed during this action. Heavy enemy mortar fire drove the gunners into their bomb-proofs, and so casements designed by Lieutenant William R. King, Corps of Engineers, US Army, Acting Chief Engineer, were added to this fort by February 1865. (Official Military Atlas of the Civil War)

Casemates

A field-fortification casemate was a stoutly constructed bomb-proof enclosure attached to the interior of a parapet for the purpose of protecting an embrasured gun position. By 1865, two of the guns in Fort Negley, in the Federal defenses at Nashville, Tennessee, had "casemates of timber, covered on the slope toward the enemy with railroad iron and made bomb-proof with earth." A Confederate six-gun battery defending Atlanta, in front of the Federal 17th Corps, was reported to have "part of the embrasures casemated" in August 1864. Casemates in more permanent fortifications consisted of vaulted masonry chambers within a rampart or wall. These were used for a variety of purposes, including both embrasured and loopholed gun positions on the flanks of bastions, curtain walls, and in caponiers. Mortar casemates open for vertical fire were also used in many polygonal system fortifications.

Merlons

In a permanent or semi-permanent fort, a battlement or a crenellation consisted of a parapet with open spaces for shooting. The raised portions of a battlement were called merlons, and the openings were known as embrasures. Merlons were constructed from various materials, including sandbags, gabions, or barrels filled with soil, sods of earth, and cotton bales. The merlons in the redoubt at Lee's Farm, in the Warwick-Yorktown line on the Peninsula, in 1862 were described as "extending at least five or six yards on each side," and also had heavy logs laid over the embrasures that were covered with a six-feet thickness of earth.

Guerites

A sentry box, known as a guerite, was incorporated into several semi-permanent Federal field fortifications such as Fort Lincoln in the Washington defenses, and Fort Negley at Nashville, Tennessee. These were square or octagonal with conical roofs and were usually placed on the superior slopes of parapets to provide sentinels with protection from the elements and a good view of the near approaches to a fortification.

A detachment of Co. K, 3rd Massachusetts Heavy Artillery manning guns either side of a gabionade defilade traverse at Fort Stevens,Washington, DC in 1865. President Abraham Lincoln came under fire at this fort during Early's attack on the Federal capital in July 1864. (Library of Congress B817-7692)

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Traverses

Traverses were raised mounds of earth designed to defilade, or obscure from the view of the enemy, the interior spaces of field works. They also limited the area affected by explosions that might occur within gun positions. Most traverses were given a rectangular outline with sides that sloped inwards from the base. Defilade traverses were usually connected at right angles to the parapet. Those made to intercept the fire of heavy siege and garrison guns could be 12- to 18-feet thick, while those designed to withstand prolonged bombardments were 24- to 40-feet thick. Traverses in rifle trenches, such as those in the "Bloody Angle" at Spotsylvania Court House in 1864, would only need to be two- to three-feet thick to intercept small-arms fire.

Parados traverses were positioned independently of the parapet and across the terre-parade of field works in order to intercept ricochet fire. When extended the full width of the terre-parade, a parados traverse could be pierced with access galleries that allowed movement from one side to the other. A parados traverse could also serve as a bomb- or splinter-proof shelter. Sally port traverses were placed on the terre-parade immediately behind a sally port entrance in order to intercept enemy fire that might otherwise pass through. They also provided the garrison with a short parapet to deliver fire into the sally port and to defend the sally port barrier.

Battery traverses were placed in batteries between guns to limit the damage caused by enemy shells exploding within the battery. They could also restrict the damage caused by accidental explosions or the premature explosion of fired shells. Not usually intended to intercept enemy fire, this type of traverse was given a splinter-proof thickness of six to eight feet, which was only capable of absorbing shell fragments. The length of a battery traverse was determined by the weight of guns forming the armament of the battery. Field guns required traverses from 15 to 18 feet long, while siege guns required traverses 18 to 24 feet long.

The defenses surrounding Washington DC originally included bomb-proof defilade traverses called gabionades. These were approximately 12 feet wide and 24 feet long at the base. Constructed with two courses of gabions interlocked by an intermediate course of fascines, they were replaced by unrevetted mounds planted over with grass to make them more durable by the end of the war.

Civil War Fascines

Constructed under the supervision of General Gouverneur K.Warren in July 1864, Federal Redoubt H, also called Fort Davis, had a parados traverse running diagonally across its terre-parade. (Official Military Atlas of the Civil War)

Gabions

A gabion was a rough cylindrical wicker basket open at both ends that was used as revetment material to retain the soil of earthwork slopes. Gabion revetments were constructed by placing a number of gabions side by side. These were filled with soil, and topped with a layer of long fascines. When greater height was required a second tier of gabions could be added on top of the fascines. Gabions were often made by engineer troops at depots near the place where they would be used. Three men could make a common gabion two feet in diameter and three feet tall in about two hours. During the siege of Yorktown, Colonel Henry J. Hunt, commanding the Federal Artillery Reserve, reported that "cannoneers of tvvo batteries at a time were detailed daily for making gabions and fascines, under direction of General [Daniel Phineas] Woodbury," who commanded the engineer brigade responsible for constructing the Yorktown siege works.

Kampfflieger Weltkrieg

These casemates were found covered by heavy timber blindage after the capture of Fort Pulaski by Federal forces in April 1862. (Library of Congress B8171 -0194)

Fascines

Used as revetment material to retain soil composing the interior slopes of parapets, and in chamber walls of field powder magazines, fascines were tightly bound bundles of brushwood and small straight branches. They were also used as foundation and topping material within gabion revetments. A fascine could also be used in gun platforms to arrest the wheels of a gun carriage and prevent the wheels from striking and damaging the interior slope. Simple field magazines could also be constructed with interior roofs composed of crossing layers of fascines. Fascines were also used to construct blindages in front, or to the rear, of batteries, and to cover the tops of saps or galleries when these works were exposed to fire from above.

These casemates were found covered by heavy timber blindage after the capture of Fort Pulaski by Federal forces in April 1862. (Library of Congress B8171 -0194)

Counterscarp galleries

In both temporary and permanent fortifications, a counterscarp gallery was a loopholed enclosure set into the counterscarp wall of a ditch. This provided cover for troops defending the ditch. A heavy door pierced with a loophole provided

Mine Creek Battlefield

Blindage

Bomb- and splinter-proof shields constructed in permanent fortifications such as forts Sumter and Pulaski were known as blindage. This form of screening was also used in field fortification to prevent an enemy from seeing into a trench or bringing accurate fire against a field work under construction. During siege operations, blindage was particularly useful for covering saps exposed to defensive fire. Blindage covering the tops of saps could simply consist of sandbags, or a layer of fascines laid over the crest of the parapet. More complex examples could consist of constructions using scantling, or thin wooden, frames anchored into forward and reverse slopes of a sap and covered by layers of fascines and earth to make them bulletproof. Blindages in front of batteries under construction were usually placed along the exterior crest of the ditch in front of the battery parapet and were made by laying several rows of gabions outside the ditch and filling them with vertically placed fascines. Although this type of blindage had sufficient height and thickness to cover working parties from enemy musket fire, it could be destroyed by artillery. As batteries were usually constructed under cover of darkness, a blindage would allow working parties to continue working during the daylight hours. However, this also made it easier for the enemy to locate battery positions and harass the work with counter-battery fire.

These impressive gabionade traverses along the interior slope of the parapet forming the right face of the right redan of Fort Sedgwick (nicknamed "Fort Hell") were photographed on April 3, 1865. Fascines are placed between the two layers of gabion. Note the empty gabion lying by the bombproof shelter. (Library of Congress B8I7I-7693)

access to the gallery from the bottom of the ditch. Counterscarp galleries could also be prepared for an artillery armament consisting of light casemate howitzers or carronades.

Glacis

More common to permanent fortifications than field fortifications, a glacis was a wide and gently sloped parapet that provided the defenders with a clear and unencumbered field of fire immediately surrounding the fortification. In field fortifications a glacis could be added along the crest of the counterscarp of the ditch to ensure that attacking troops could not avoid fire from the parapet by crawling or crouching through the last few yards immediately in front of the ditch.

Gorges

In unenclosed field fortifications consisting of continuous lines of works containing lunettes and redans, the gorge was considered to be the rear of the fortification or a fortification front not shielded by a continuous parapet. In permanent fortifications and enclosed field works such as star forts, bastion forts, and redoubts, the gorge was the main entrance or sally port, or the rear of an outwork.

Têtes-de-pont

Forts that offered protection to a bridge or river crossing point were called têtes-de-pont, and were used extensively by both Union and Confederate armies. The Federals used a tête-de-pont, consisting of forts Marcy and Ethan Allen, to protect the Chain Bridge in the Washington defenses in 1864. On the Alexandria side of the Potomac River, Fort Runyon was a large tête-de-pont guarding the approaches along the Columbia Turnpike.

Rifle pits

Rifle pits were small trenches for one or two men with a slight parapet or other cover in front. They were generally established well in advance of the outworks of a fortification or main line of field works, or on the flanks of a besieging army. With brush and branches placed in front of them to hide the occupant, they were commonly known as "gopher holes." During the siege of Atlanta, Captain O. M. Poe, Chief Engineer under Sherman, described how the Army of the Tennessee

Shelter Half Tent Civil War

Photographed by Timothy O'Sullivan in May 1864, these Federal troops occupy a rifle trench on the north bank of the North Anna River,Virginia.The men have draped their shelter-half tents over scantling, or wooden poles, to provide some protection from the elements. (Library of Congress B8I7I-0756A)

Outer field fortifications

A wide variety of hastily prepared defensive works and obstacles were used during the course of a Civil War battle. Rifle trenches connected larger works, while rifle pits were placed in advance of them. Once the ground had been cleared of all natural and man-made obstructions in front of more permanent field works, these could be employed with even greater effect to impede the advance of an attacking body of troops. Different types of obstacles could be placed either just beyond the crest of the counterscarp of a parapet, where the enemy could be hit with close-range musket fire, or within the ditch itself to prevent the enemy from passing through and scaling the scarp. Further obstacles could be placed in the actual trenches to prevent the enemy from taking advantage once a section of trench had been captured. An illustration of a rifle trench is shown on page 22.

employed rifle pits and linked them together to form rifle trenches. Each man got "such cover as he could, generally by scooping out a rifle-pit at the foot of a tree, behind a log or stone, in which they could find shelter. As soon as night made it possible, working parties were thrown out to the skirmish line and connected by the ordinary rifle trenches the entire chain of rifle-pits. These lines were continually being strengthened until it was desired to make another advance, when the operation was repeated. In this way our lines were pushed at any point we wished to within 200 yards of the enemy's and with slight loss."

Breastworks Battlefield

Despite Grant's insistence that entrenching tools be carried by each of his columns, artist Alfred Waud was able to sketch elements of Hancock's 2nd Army Corps frantically throwing up breastworks using bayonets, tin pans, old canteens, and even their hands, at Cold Harbor on June 3, 1864. (Battles & Leaders)

Breastworks

The term breastwork more commonly refers to any protective embankment that could be raised rapidly, using logs, rails, or rocks, in order to provide infantry with cover to the level of the chest, or breast. According to the report of Colonel Thomas Pattison, 18th Indiana Infantry, it took his men about five hours to build "quite a respectable breastwork" during the Battle of Pea Ridge, or Elk Horn Tavern, Arkansas, on March 6, 1862. "Slight" breastworks referred to those defenses behind which infantry might crouch. Masked breastworks, such as those used at Big Bethel in 1861, were used to surprise and repulse an advancing enemy force. Breastworks were particularly useful on wet ground with a high water table that prevented the excavation of a deep ditch or trench. Soil for construction could be taken from shallow trenches both in front and to the rear of the parapet. This also applied to ground where a thin layer of topsoil covered a solid rock bed. Breastworks were also useful when positioned along the crest of a ridge, where enemy troops approaching the work, or standing near the foot of the exterior slope, could not see over the parapet.

Despite Grant's insistence that entrenching tools be carried by each of his columns, artist Alfred Waud was able to sketch elements of Hancock's 2nd Army Corps frantically throwing up breastworks using bayonets, tin pans, old canteens, and even their hands, at Cold Harbor on June 3, 1864. (Battles & Leaders)

Barricades

An obstruction placed on a battlefield to block the passage of the enemy, barricades were formed using whatever materials were close at hand, such as felled trees, cotton bales, tipped-over wagons, and fence rails. They could also be constructed using regular obstacles such as chevaux-de-frise or palisades. Sometimes they were arranged to include a makeshift banquette to enable the defenders to fire over the barricade. They might also have loopholes to facilitate fire through the material composing the obstacle. Both armies used barricades to afford makeshift defensive positions during many of the major battles of the war. The construction of barricades in some regiments was the job of pioneers equipped with axes.

When the Union army marched out from the Washington defenses in July 1861, the Confederates placed barricades across the roads leading to Manassas. After Malvern Hill in 1862, Colonel Charles W. Roberts, 2nd Maine Infantry, reported: "Having the advantage of a rail fence, I ordered my boys to make with their knapsacks a barricade, which they did in a very short time. In this position we remained nearly two hours, waiting for the enemy."

During the Yazoo River expedition in Mississippi during January 1863, Lieutenant Colonel James H. Wilson, Chief of Topographical Engineers, Union Army of the Tennessee, encountered deserted barricades erected by the Confederates that were about two miles in length. " 1 hey were formed by felling trees into and across the stream," he reported. "The forest being very dense, and the growth luxuriant, the trees were of the largest and heaviest kinds, cottonwood, sycamore, oak, elm, and pecan prevailing, and all, except cottonwood, having a greater specific gravity than water. These, mixed with drift-wood, rendered the barricade of no trifling nature."

Cavaliers

A cavalier in a permanent fort was a raised work that commanded fire over outer works or surrounding ground. Reported in the Confederate defenses of both Richmond and Petersburg, cavaliers wTere trenches with their parapets raised high enough to see over the crest of the glacis. Constructed on top of a raised mound or small rampart, a cavalier battery was constructed in Fort McPherson at Louisville, Kentucky, in October 1864, while a cavalier was built over a magazine in the defenses of Mobile, Alabama, during the same period.

This drawing by Edwin Forbes shows members of the Pennsylvania Reserves behind a barricade made from fence rails, resisting a Confederate attack near the Bethesda Church during the battle at Cold Harbor. (Battles & Leaders)

Covered ways

Sunken roads known as covered ways, wide enough to accommodate the free circulation of troops and the passage of wagons and artillery, connected two or more field works through ground exposed to enemy fire. A parapet protected the side of the road facing the enemy. In permanent fortifications covered ways were outworks that ran parallel to the crest of the counterscarp. This allowed the garrison to guard and defend the glacis.

Fortifications

Detail from a plate in Mahan's Treatise on Field Fortification showing a plan and cross section of an arrangement of conical trous-de-loup, small pyramidal pits with pickets, and an advanced glacis and abatis. (Author's collection)

FortificationsAbatis ModernFortifications

These sections of chevaux-de-frise were found in place before the Confederate field works at Petersburg in 1865. (Library of Congress B81 I-3206A)

Parallels

Used to provide defensive positions that allowed a besieging army to hold the ground gained in its approaches to a fortified position, parallels were laid out either parallel to the point of attack or on a concentric line that enveloped it. As the besieging army drew closer to its objective, parallels were also used as forward supply depots. If threatened by enemy sorties, the fronts of the parallels could be protected by obstacles such as abatis or palisading, though the extra labor involved in constructing extensive obstacles was usually too expensive in time and material for most attacking armies.

Boyaux

Communication trenches that provided covered passage to and from parallels and batteries were known as boyaux. For infantry these were usually about four to five feet wide, which was sufficient for the passage of two men. Dimensions had to be increased when it was necessary to pass artillery through the trenches rather than move guns and howitzers into position over open ground under

Basic field fortifications

The upper illustration shows the main features of a parapet and ditch. Ground level (I) was referred to as the "plane of the site." The area enclosed within the parapet was known as the terre-plein (2).The ground sloping up from this was the banquette slope (3).The raised earthen platform on which the garrison stood to defend the work was the banquette tread (4).The inner face of the parapet was called the interior slope (5), supported by a gabion revetment with a fascine base; at the top of the slope was the interior crest (6).The top surface of the parapet was known as the superior slope (7), which terminated at the exterior crest (8).The outer face of the parapet was the exterior slope (9), at the bottom of which was the berme (10).The side of the ditch facing the enemy was the scarp (I I), and was often pierced with a fraise (12); the bottom of the ditch (13) could also have sharpened palisading.The opposite facing edge of the ditch is the counterscarp (14), and the ground sloping gently away from this was the glacis (15) containing abatis (16).

The lower illustration shows a rifle trench, the single most common form of field fortification employed during the Civil War; these were often used to defend the intervals in between large works. Notched or loopholed timbers placed along the crest of the parapet enabled men to fire on the enemy without being seen. Alternatively, a headlog (A) was placed along the top of the parapet, resting on top of blocks, or skids (B), c. one foot from the interior crest of the parapet; the skids' purpose was to catch the log if it happened to be struck by artillery and send it rolling over the heads of the men in the trench. Headlogs were usually pinned in place using small pickets (C). Alternatively, sandbag loopholes were formed by placing two sandbags a few inches apart on the parapet. Crossbeams were also sometimes inserted across the top of a trench to provide shelter against the elements or the collapse of soil.

cover of darkness. On August 5, 1864, Captain G. H. Mendell, commanding the US Engineer Battalion during the siege of Petersburg, reported that 17,200 feet of boyaux, averaging nine feet in width and three and a half feet in depth, had been constructed in the Federal trenches.

Carnot walls

Incorporated into the Richmond defenses by 1863, Carnot walls were named after the French general Lazare Nicholas Marguerite Carnot (1753-1823), and were part of a system of "active defense." To facilitate sorties in great force, Carnot did away with a counterscarp wall, and provided instead a long gentle slope from the bottom of the ditch to the crest of the glacis. This, he believed, would compel an assailant to maintain large forces in the advanced trenches, which he proposed to attack by vertical fire from mortars. Along the front of his fortress was built a heavy detached wall that was loopholed for fire, and high enough to be a most formidable obstacle. The Carnot wall, and, in general, Carnot's principle of active defense, played a great part in the rise of modern fortification.

Chevaux-de-frise

An obstacle called a cheval-de-frise (pi. chevaux-de-frise), or "horse of Friesland," was possibly invented by the Dutch during the siege of Groningen in 1594, and usually consisted of a nine- to ten-feet long horizontal beam pierced by two diagonal rows of ten-foot-long, sharpened lances. Hooks and chains were attached to the ends of the beams to allow several chevaux-de-frise to be bound together. This type of obstacle was free-standing and hence ideal for covering the front of field works when the danger of exposure to hostile fire, even at night, was too great to permit working parties to construct more solidly fixed obstacles. It also did effective service in the

These roughly hewn Confederate chevaux-de-frise was photographed on Marietta Street in the Atlanta defenses in 1864. (Library of Congress B8I I-2724A)

Mine Creek Battlefield

Abatis

Referred to as "an obstructing jungle" by Confederate Major J. F. Gilmer, Chief Engineer of the Western Department, in November 1861, abatis consisted of felled trees stripped of their leaves and smaller off-shoots, with remaining branches sharpened into points. These were placed side-by-side and staked down with the sharpened branches pointing towards the enemy. Their purpose, like other obstacles exterior to the ditch, was to break the momentum of an assaulting body of troops and hold them up under close musket fire delivered from the defensive position.

As early as February 1861, Lieutenant A. J. Slemmer, 1st US Artillery, reported that "an abatis of brush" had been placed about the exposed points of attack at Fort Pickens, in Florida. According to Brigadier General Charles F. Smith, commanding Union forces at Paducah, in Kentucky, during the fall of 1861, "a very sufficient abatis, several hundred yards in width" formed part of the defense of that place. Artificial, or incompletely made, abatis were used in the defenses around Washington, DC to confuse the enemy.

Not all combatants respected the field works there to protect them. Later in the war, Major James C. Duane, US Engineers, reported that portions of the Federal abatis between batteries 11 and 12 outside Petersburg had been "taken away by the pickets for fire-wood."

These roughly hewn Confederate chevaux-de-frise was photographed on Marietta Street in the Atlanta defenses in 1864. (Library of Congress B8I I-2724A)

bottom of ditches and in the entrance to field works.

A second type of cheval-de-frise, often referred to as "palisading," was constructed using a stout, sharpened timber stake to which one or more legs were attached to secure it in an inclined position pointing in the direction of an expected enemy attack. When a number of chevaux-de-frise were positioned close together it created an inclined palisading.

Breastwork Timbers
Taken from Fort Sedgwick outside the Petersburg lines on April 3, 1865, this photograph shows a fraise and deep ditch in front of the breastworks. (Library of Congress B81 I-3209A)

Trous-de-loup

Also called "military pits," these obstacles were usually sited beyond the crest of the counterscarp and consisted of an arranged pattern of pits about six feet in diameter and six feet deep with a sharpened picket, or post, planted at the bottom. The pits were often concealed with a light layer of brushwood and soil. Trous-de-loup were used near Charleston, South Carolina, at Secessionville in 1862, and in front of Battery Wagner, in 1863. At the latter location they were combined with "boards with sharp nails or spikes in the bottom of the ditches." They were later placed in front of the Union lines around Petersburg, Virginia, during March 1865.

Praises

A fraise was an obstacle consisting of palisades projecting horizontally from the scarp or counterscarp of the ditch of a temporary fortification. In the former, a fraise was designed to inhibit attacking troops who had already entered the ditch from scaling the scarp to reach the parapet. When positioned just below the crest of the counterscarp, a fraise was designed to prevent attacking troops from entering the ditch or escaping from it if their attack failed. An interval of 12 feet had to be left between the extremities of the palisades and the opposite side of the ditch to prevent attacking troops from using ladders or planks to bridge the gap and cross the ditch.

Wire entanglements

Although James F. Glidden did not invent true barbed wire for use on the Western plains until 1873, smooth telegraph wire was readily available by 1863. During the Union retreat from Winchester towards Harper's Ferry, Virginia, in May of that year, Major Alonzo W. Adams, 1st New York Cavalry, reported that the Confederates had created "a perfect barricade of telegraph wire wound together and stretched from tree to tree across roads and through woods and fields, so as to completely obstruct the farther progress of cavalry."

Wire entanglement appears to have been used quite extensively by the Federal army during the siege of Knoxville in November 1863. Stretched from one tree stump to another, it delayed the attack on Fort Sanders and contributed to a Federal victory.

On November 16, 1864, wire was also placed in front of the siege works to the right of Fort Fisher on the Petersburg lines. Completed in two days, this ran west and terminated about 200 yards to the left of Fort Welch, in the lines to the southwest of the city. On this occasion, it was employed "to take the place of slashings [abatis] removed by the troops." More wire entanglement was placed around Fort Fisher during February 1865.

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