General William Tecumseh Sherman wrote, “…earthworks play an important part in war, because they enable a minor force to hold a superior one in check for a time, and time is a most valuable element in all wars.” Frederick the Great said, “Officers require different kinds of knowledge, but one of the principal is that of fortification.” In fact, 18th and 19th century treatises in war placed the entrenching tool almost on a level with the musket. Military leaders understood that against well entrenched troops, an assault often resulted in numbers of losses equal to the entire force opposed to attack; something British General William Howe learned all too well at the Battle of Bunker Hill, June 17, 1775. In North America, where military fortifications were frequently constructed in relatively remote and inaccessible locations, works built from readily available materials (typically brick, lumber and earth) tended to be more common than the ornate stone and masonry edifices of Europe. Because of the nature of these building materials, most of these works were transitory, and have not survived to the present. Such importance was placed on fortifications that we turn once more to General Sherman who wrote, “a well entrenched line, defended by two ranks of infantry cannot be carried by a direct attack.”
Fortification is the artificial means used to give additional strength to a position. It is derived from the Latin fortis meaning strong and facers to make. The skillful combination of these means, and their construction constitute a branch of military engineering known as “The Art of Fortification.” The object of fortification is first and foremost to strengthen positions selected for defense. There are two classes of fortifications – permanent & temporary.
Permanent Fortifications were usually constructed in peace time for the purpose of strengthening positions of military importance in the advent of war. They were built with great care over considerable time, of durable goods and were expected to last; such as the forts, castles, and walled cities of Europe. In 17th and 18th North America, only a few such forts were constructed to stand the test of time. The walled city and citadel at Quebec, the stone fortress at Ticonderoga New York, built by the French and further strengthened by the British, redoubts at West Point, and Fort George at the tip of Manhattan Island, originally constructed by the Dutch using slave labor and later enlarged by the British and Americans, torn down as the city’s commercial district expanded.
Temporary Fortifications were thrown up after war had been declared and or to strengthen positions which had suddenly acquired military importance. Most of the works constructed during the French & Indian War and The American Revolution were of this class. These earthen works were built in a comparatively short time using materials which were near at hand and could be obtained quickly from the surrounding woods and countryside. The construction was frequently by the labor of troops, in some cases slave labor, and were overseen by military engineers or experienced officers. The materials were often wanting in durability, and were therefore temporary in their nature. Though this class might in some cases become permanent, the positions strengthened by them were frequently of transitory importance and soon abandoned. There were two types of fortifications – hasty and ordinary.
Hasty Fortifications were those built from the time a body of troops ended their march and the beginning of a battle. The allotted time was usually a few hours or a single night, often constructed in the presence of the enemy. A good example of a hasty fortification was the substantial redoubt thrown up on Breeds Hill between midnight and the morning of June 17, 1775 – an impressive earthwork that proved devastating to the attacking British.
Ordinary Fortifications were also constructed hurriedly, but there was time enough to practically finish them according to plans upon which they were laid out. Examples that come to mind are: the extensive redoubts and earthworks built around New York City in 1776 just prior to the British Armada’s arrival, the earthworks that successfully defended Charleston, South Carolina on June 28, 1776 against the first British invasion, and Mt. Independence – the redoubt and connecting lines that were hurriedly thrown up on the other side of Lake Champlain from fort Ticonderoga in preparation to repel British General Burgoyne’s advancing army.
The American Army was forced to fortify their positions. The American forces almost always met the criteria for the necessity of fortifications; enabling an armed force occupying the fortified position to contend successfully against an assault, superior either in numbers, discipline, or arms. In almost all cases, from the initial clash of arms until the advent of French troops assisting the Americans, the English (including German mercenaries) were better equipped, thoroughly trained, and strictly disciplined. Veteran troops were led by competent, experienced officers who rose through the ranks after years of campaigning in uniform. Opposed to this professional army were a collection of citizen soldiers, a ‘rabble in arms,’ whose weapons were most often family muskets, absent of bayonets, and mainly officered by local town officials, farmers, lawyers, and wealthy merchants; few with acquired military skills. This clash between professionals and amateurs prompted General Henry (Light Horse Harry) Lee to write “…a government is the murderer of its citizens which sends them to the field uniformed and untaught, where they are to meet men of the same age & strength, mechanized by education and discipline for battle…”
Such a citizen army relied heavily on the proven merits of fortifications which allowed the American ‘rebels’ to meet the challenge of facing a far superior force. General Israel Putnam may have said it best just prior to the Battle of Bunker Hill, when he supposedly spoke at a Council of War to discuss the construction of a fortification: “The Americans are not at all afraid of their heads, though very much afraid of their legs; if you cover those, they will fight forever.”
Principals of Fortifications. Here we refer to Wheeler’s text on The Elements of Field Fortification, which best describes the four basic principals. For a defensive force to contend successfully against a superior force either in numbers, discipline, or arms, conditions must be favorable to the defense and unfavorable to the assailant – conditions provided by the fortification.
A shelter must be provided to protect the defenders against the missiles of the assailant, and to screen them from view. This was usually satisfied by enacting an excavation, and heaping the mass of earth thus obtained, until it was high enough and thick enough to screen and protect the defenders.
The position should be so arranged that an assailant can not approach without cannon range and not be exposed to the fire of the defense. This was ordinarily achieved by clearing away the ground in front of the position, and within cannon range, of all trees, houses, enclosures, hedges, fences, filling depressions, etc. – anything that might be used by the enemy as a screen. The defenders would fire over it or through it and sweep the ground with their fire over which the enemy had to approach. This proved highly successful for the two Rhode Island regiments who defended the expanded redoubts at the Battle of Redbank (Oct. 22, 1777) against a far superior Hessian force. Four hundred Americans poured fire into ‘killing fields’ packed tightly with Hessians that inflected crushing casualties on the assaulting division of Germans numbering over two thousand.
If practicable, the position and shelter should be arranged so that an approach of the enemy would be difficult, and the enemy’s movements towards the position be greatly impeded. This was met by placing the fortification behind a natural obstruction, such as a marsh or water course. Also, obstacles were put in front of the earthworks, such as an abatis of sharpened tree branches outwards towards the enemy. They would be arranged so that they would impede the assailant’s approach, but not screen his movement, nor protect him from the fire of the defense. The British futile assault on Fort Carillon (renamed Fort Ticonderoga) on July 8, 1758 was a good example. The redcoats were cut to pieces by French fire as they hacked through the abatis and tried to scale the walled embankments.
The position and shelter should be arranged so that the defenders’ movements to defend the position should not be hindered or impeded in any way. This complied with the removal of any obstructions which might have been in the way of free movements of the defense. This also applied to establishing rapid communications within the fortification.
Passive and Active describe the type of resistance offered by the defense. If there is no motion to leave the works to attack the enemy, it is termed passive. This was usually in the face of a far superior force or if the goal of the defense was to maintain its position after the enemy failed in their assault. An active resistance occurred if the defenders left the position and attacked prior to the assault, or if they saw an opportune movement and left the position during the attack for the same purpose. An active defense could be made, as a rule, only by a force which was strong enough and numerous enough to leave the defense with the chance of a successful attack. An example would be if the defense were reinforced such as was the case in the 1779 Siege of Savannah. The British were reinforced prior to the French and American main assault, resulting in the failed attack and successful counterattacks by the British. Also the Battle of Rhode Island in which the Americans lost their support when the French fleet sailed away, allowing the British to emerge from their defensive positions and attack the Americans in force.
The Principal Parts of a constructed fortification or earthen shelter were the mass of earth heaped up and the excavation from which it was taken. When the excavation was between the mass of earth and the enemy, it was called a ditch; as at Crown Point, New York in which a very high defensive earthwork sits behind and above a deep depression from which the earth was taken. If the mass of earth is between the excavation and the enemy, such as what was constructed at Bunker (Breed’s) Hill, then it was a trench – the simplest form of shelter. At Breeds Hill, the earth was leveled and heaped up in front of the excavated site from which the defenders fired down upon the ascending enemy.
Fortifications share common features. Outside a few exceptions, the most common fortifications constructed before and during the American Revolutionary War took the form of redoubts – from small constructions to large scale forts, often built by the troops detailed to man the earthworks. They all shared basic common features: parapet, banquette, embrasures, ditch (with berm, scarp, and counter-scarp), palisades, fraizes, abbatis, and entrance.
Each of these will be described in detail in the companion post to this article which the reader may visit by clicking the underlined title:
For Further Reading on Forts and the American Revolution, check out these free previews on Amazon
Articles on artillery and field cannon in Revolutionary War Journal
SOURCES
Fraser, Capt. T. The Defence of a Position Selected as a Field of Battle – Royal Engineer Prize Essay. 1875: A. W. & J. P. Jackson Printers, New York, NY.
Historic Structures Report The Redoubts of West Point Douglas R. Cubbison January 2004
Lochlee, Lewis. Elements of Field Fortification. 1783: T. Cadell & T. Egerton, London, England.
Office of the Chief of Military History. Selected Quotes of United States Military Leaders. 1964: Dept. of the Army, Washington D. C.
Pleydell, Lt. J. C. An Essay on Field Fortification: Intended Principally for the use of Officers of Infantry… 1768: J. Nourse Bookseller to His Majesty & 1790: Printed for F. Wingrave, London, England.
Wheeler, J. B. The Elements of Field Fortifications for the Use of the Cadets of the United States Military Academy, at West Point, New York. 1893: D. Van Nostrand Company, New York, NY.