Fortification

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v t e

A fortification (also called a fort, fortress, fastness, or stronghold) is a

From very early history to modern times,

or fortress. These constructions mainly served the purpose of a watch tower, to guard certain roads, passes, and borders. Though smaller than a real fortress, they acted as a border guard rather than a real strongpoint to watch and maintain the border.

The art of setting out a military camp or constructing a fortification traditionally has been called "castrametation" since the time of the Roman legions. Fortification is usually divided into two branches: permanent fortification and field fortification. There is also an intermediate branch known as semipermanent fortification.^[2] Castles are fortifications which are regarded as being distinct from the generic fort or fortress in that they are a residence of a monarch or noble and command a specific defensive territory.

saw the creation of some towns built around castles.

Medieval-style fortifications were largely made obsolete by the arrival of

that would absorb and disperse the energy of cannon fire. Walls exposed to direct cannon fire were very vulnerable, so the walls were sunk into ditches fronted by earth slopes to improve protection.

The arrival of

have made large-scale fortifications obsolete in most situations.

History

Early uses

Defensive fences for protecting humans and domestic animals against predators was used long before the appearance of writing and began "perhaps with primitive man blocking the entrances of his caves for security from large carnivores".^[3]

From very early history to modern times,

Bronze Age Europe

In

a few miles away.

In

murus gallicus. Oppida were large fortified settlements used during the Iron Age

.

The Oppidum of Manching (German: Oppidum von Manching) was a large Celtic proto-urban or city-like settlement at modern-day Manching (near Ingolstadt), Bavaria (Germany). The settlement was founded in the 3rd century BC and existed until c. 50–30 BC. It reached its largest extent during the late La Tène period (late 2nd century BC), when it had a size of 380 hectares. At that time, 5,000 to 10,000 people lived within its 7.2 km long walls. The oppidum of Bibracte is another example of a Gaulish fortified settlement.

The term casemate wall is used in the archeology of Israel and the wider Near East, having the meaning of a double wall protecting a city^[14] or fortress,^[15] with transverse walls separating the space between the walls into chambers.^[14] These could be used as such, for storage or residential purposes, or could be filled with soil and rocks during siege in order to raise the resistance of the outer wall against battering rams.^[14] Originally thought to have been introduced to the region by the Hittites, this has been disproved by the discovery of examples predating their arrival, the earliest being at Ti'inik (Taanach) where such a wall has been dated to the 16th century BC.^[16] Casemate walls became a common type of fortification in the Southern Levant between the Middle Bronze Age (MB) and Iron Age II, being more numerous during the Iron Age and peaking in Iron Age II (10th–6th century BC).^[14] However, the construction of casemate walls had begun to be replaced by sturdier solid walls by the 9th century BC, probably due the development of more effective battering rams by the Neo-Assyrian Empire.^[14][17] Casemate walls could surround an entire settlement, but most only protected part of it.^[18] The three different types included freestanding casemate walls, then integrated ones where the inner wall was part of the outer buildings of the settlement, and finally filled casemate walls, where the rooms between the walls were filled with soil right away, allowing for a quick, but nevertheless stable construction of particularly high walls.^[19]

Aurelian walls near Porta San Sebastiano

The

Lincoln

.

(AD 76–138) in AD 122.

Indian subcontinent

A number of forts dating from the

India currently has over 180 forts, with the state of Maharashtra alone having over 70 forts, which are also known as durg,^[24][25][26] many of them built by Shivaji, founder of the Maratha Empire.

A large majority of forts in India are in North India. The most notable forts are the

Arthashastra, the Indian treatise on military strategy describes six major types of forts differentiated by their major modes of defenses.

Kashyapa I of Anuradhapura

.

Forts in

during the two world wars. Most of these were abandoned by the military but retained civil administrative officers, while others retained military garrisons, which were more administrative than operational. Some were reoccupied by military units with the escalation of the , for example, came under siege several times.

Large tempered earth (i.e.

(1368–1644 AD).

In addition to the Great Wall, a number of Chinese cities also employed the use of defensive walls to defend their cities. Notable Chinese city walls include the city walls of Hangzhou, Nanking, the Old City of Shanghai, Suzhou, Xi'an and the walled villages of Hong Kong. The famous walls of the Forbidden City in Beijing were established in the early 15th century by the Yongle Emperor. The Forbidden City made up the inner portion of the Beijing city fortifications.

During the

. Of all the buildings within the 67-acre city, only one building, the San Agustin Church, survived the war.

Partial listing of Spanish forts:

1. Intramuros, Manila
2. Cuartel de Santo Domingo, Santa Rosa, Laguna
3. Fuerza de Cuyo
   , Cuyo, Palawan
4. Fuerza de Cagayancillo
   , Cagayancillo, Palawan
5. Real Fuerza de Nuestra Señora del Pilar de Zaragoza, Zamboanga City
6. Fuerza de San Felipe, Cavite City
7. Fuerza de San Pedro, Cebu
8. Fuerte de la Concepcion y del Triunfo, Ozamiz, Misamis Occidental
9. Fuerza de San Antonio Abad, Manila
10. Fuerza de Pikit, Pikit, Cotabato
11. Fuerza de Santiago, Romblon, Romblon
12. Fuerza de Jolo, Jolo, Sulu
13. Fuerza de Masbate, Masbate
14. Fuerza de Bongabong,
    Bongabong, Oriental Mindoro
15. Cotta de Dapitan, Dapitan, Zamboanga del Norte
16. Fuerte de Alfonso XII,
    Tukuran, Zamboanga del Sur
17. Fuerza de Bacolod, Bacolod, Lanao del Norte
18. Guinsiliban Watchtower,
    Guinsiliban, Camiguin
19. Laguindingan Watchtower,
    Laguindingan, Misamis Oriental
20. Kutang San Diego,
    Gumaca, Quezon
21. Baluarte Luna, Luna, La Union

The Ivatan people of the northern islands of Batanes built their so-called

to protect themselves during times of war. These fortifications were likened to European castles because of their purpose. Usually, the only entrance to the castles would be via a rope ladder that would only be lowered for the villagers and could be kept away when invaders arrived.

The Igorots built forts made of stone walls that averaged several meters in width and about two to three times the width in height around 2000 BC.^[29]

The Muslim Filipinos of the south built strong

Many of these forts were also destroyed by American expeditions, as a result, very very few kotas still stand to this day.

Notable kotas:

• Bruneian Empire in Luzon, later became the City of Manila
  .
• Kuta Wato/Kota Bato: Literally translates to "stone fort" the first known stone fortification in the country, its ruins exist as the "Kutawato Cave Complex"^[31]
• Kota Sug/Jolo: The capital and seat of the Sultanate of Sulu. When it was occupied by the Spaniards in the 1870s they converted the kota into the world's smallest walled city.

During

During the Siege of Ta'if in January 630,^[33] Muhammad ordered his followers to attack enemies who fled from the Battle of Hunayn and sought refuge in the fortress of Taif.^[34]

The entire city of Kerma in Nubia (present day Sudan) was encompassed by fortified walls surrounded by a ditch. Archeology has revealed various Bronze Age bastions and foundations constructed of stone together with either baked or unfired brick.^[35]

The

A military tactic of the

Defensive works were of importance in the tropical African Kingdoms. In the Kingdom of Kongo field fortifications were characterized by trenches and low earthen embankments. Such strongpoints ironically, sometimes held up much better against European cannon than taller, more imposing structures.^[42]

. From the 12th century, hundreds of settlements of all sizes were founded all across Europe, which very often obtained the right of fortification soon afterward.

The founding of urban centers was an important means of territorial expansion and many cities, especially in

.

Medieval-style fortifications were largely made obsolete by the arrival of

that would absorb and disperse the energy of cannon fire. Walls exposed to direct cannon fire were very vulnerable, so were sunk into ditches fronted by earth slopes.

This placed a heavy emphasis on the geometry of the fortification to allow defensive cannonry interlocking fields of fire to cover all approaches to the lower and thus more vulnerable walls.

The evolution of this new style of fortification can be seen in transitional forts such as Sarzanello^[43] in North West Italy which was built between 1492 and 1502. Sarzanello consists of both crenellated walls with towers typical of the medieval period but also has a ravelin like angular gun platform screening one of the curtain walls which is protected from flanking fire from the towers of the main part of the fort. Another example is the fortifications of Rhodes which were frozen in 1522 so that Rhodes is the only European walled town that still shows the transition between the classical medieval fortification and the modern ones.^[44] A manual about the construction of fortification was published by Giovanni Battista Zanchi in 1554.

Fortifications also extended in depth, with protected batteries for defensive cannonry, to allow them to engage attacking cannons to keep them at a distance and prevent them from bearing directly on the vulnerable walls.

sea fortress from 18th century in Helsinki

, Finland

The result was

being fine examples.

19th century

During the 18th century, it was found that the continuous

Gone were citadels surrounding towns: forts were to be moved some distance away from cities to keep the enemy at a distance so their artillery could not bombard said urbanized settlements. From now on a ring of forts were to be built at a spacing that would allow them to effectively cover the intervals between them.

The arrival of

Star forts

did not fare well against the effects of high explosives and the intricate arrangements of bastions, flanking batteries and the carefully constructed lines of fire for the defending cannon could be rapidly disrupted by explosive shells.

Worse, the large open ditches surrounding forts of this type were an integral part of the defensive scheme, as was the covered way at the edge of the counterscarp. The ditch was extremely vulnerable to bombardment with explosive shells.

In response, military engineers evolved the polygonal style of fortification. The ditch became deep and vertically sided, cut directly into the native rock or soil, laid out as a series of straight lines creating the central fortified area that gives this style of fortification its name.

Wide enough to be an impassable barrier for attacking troops but narrow enough to be a difficult target for enemy shellfire, the ditch was swept by fire from defensive

set in the ditch as well as firing positions cut into the outer face of the ditch itself.

The profile of the fort became very low indeed, surrounded outside the ditch covered by

by a gently sloping open area so as to eliminate possible cover for enemy forces, while the fort itself provided a minimal target for enemy fire. The entrypoint became a sunken gatehouse in the inner face of the ditch, reached by a curving ramp that gave access to the gate via a rolling bridge that could be withdrawn into the gatehouse.

Much of the fort moved underground. Deep passages and tunnel networks now connected the blockhouses and firing points in the ditch to the fort proper, with magazines and machine rooms deep under the surface. The guns, however, were often mounted in open emplacements and protected only by a parapet; both in order to keep a lower profile and also because experience with guns in closed casemates had seen them put out of action by rubble as their own casemates were collapsed around them.

The new forts abandoned the principle of the bastion, which had also been made obsolete by advances in arms. The outline was a much-simplified polygon, surrounded by a ditch. These forts, built in masonry and shaped stone, were designed to shelter their garrison against bombardment. One organizing feature of the new system involved the construction of two defensive curtains: an outer line of forts, backed by an inner ring or line at critical points of terrain or junctions (see, for example, Séré de Rivières system in France).

Traditional fortification however continued to be applied by European armies engaged in warfare in colonies established in Africa against lightly armed attackers from amongst the indigenous population. A relatively small number of defenders in a fort impervious to primitive weaponry could hold out against high odds, the only constraint being the supply of ammunition.

today.

The downfall of permanent fortifications had two causes:

• The ever-escalating power, speed, and reach of artillery and airpower meant that almost any target that could be located could be destroyed if sufficient force were massed against it. As such, the more resources a defender devoted to reinforcing a fortification, the more combat power that fortification justified being devoted to destroying it, if the fortification's destruction was demanded by an attacker's strategy. From World War II, bunker busters were used against fortifications. By 1950, nuclear weapons were capable of destroying entire cities and producing dangerous radiation. This led to the creation of civilian nuclear air raid shelters.
• The second weakness of permanent fortification was its very permanency. Because of this, it was often easier to go around a fortification and, with the rise of mobile warfare in the beginning of World War II, this became a viable offensive choice. When a defensive line was too extensive to be entirely bypassed, massive offensive might could be massed against one part of the line allowing a breakthrough, after which the rest of the line could be bypassed. Such was the fate of the many defensive lines built before and during World War II, such as the Siegfried Line, the Stalin Line, and the Atlantic Wall. This was not the case with the Maginot Line; it was designed to force the Germans to invade other countries (Belgium or Switzerland) to go around it, and was successful in that sense.^[47]

Instead field fortification rose to dominate defensive action. Unlike the trench warfare which dominated World War I, these defenses were more temporary in nature. This was an advantage because since it was less extensive it formed a less obvious target for enemy force to be directed against.

If sufficient power were massed against one point to penetrate it, the forces based there could be withdrawn and the line could be reestablished relatively quickly. Instead of a supposedly impenetrable defensive line, such fortifications emphasized

, so that as defenders were forced to pull back or were overrun, the lines of defenders behind them could take over the defense.

Because the mobile offensives practiced by both sides usually focused on avoiding the strongest points of a

, these defenses were usually relatively thin and spread along the length of a line. The defense was usually not equally strong throughout, however.

The strength of the defensive line in an area varied according to how rapidly an attacking force could progress in the terrain that was being defended—both the terrain the defensive line was built on and the ground behind it that an attacker might hope to break out into. This was both for reasons of the strategic value of the ground, and its defensive value.

This was possible because while offensive tactics were focused on mobility, so were defensive tactics. The dug-in defenses consisted primarily of infantry and

behind the defensive line. If a major offensive was launched against a point in the line, mobile reinforcements would be sent to reinforce that part of the line that was in danger of failing.

Thus the defensive line could be relatively thin because the bulk of the fighting power of the defenders was not concentrated in the line itself but rather in the mobile reserves. A notable exception to this rule was seen in the defensive lines at the Battle of Kursk during World War II, where German forces deliberately attacked the strongest part of the Soviet defenses, seeking to crush them utterly.

The terrain that was being defended was of primary importance because open terrain that tanks could move over quickly made possible rapid advances into the defenders' rear areas that were very dangerous to the defenders. Thus such terrain had to be defended at all costs.

North American Aerospace Defense Command

. Cheyenne Mountain is an example of a mid-20th century fortification built deep in a mountain.

In addition, since in theory the defensive line only had to hold out long enough for mobile reserves to reinforce it, terrain that did not permit rapid advance could be held more weakly because the enemy's advance into it would be slower, giving the defenders more time to reinforce that point in the line. For example, the

in Germany during the closing stages of World War II is an excellent example of how difficult terrain could be used to the defenders' advantage.

After World War II,

have been used as hidden defenses in modern warfare, often remaining long after the wars that produced them have ended.

Demilitarized zones along borders are arguably another type of fortification, although a passive kind, providing a buffer between potentially hostile militaries.

by ground forces, stand-off attacks (mortars and rockets), air attacks, or ballistic missiles. Key targets—aircraft, munitions, fuel, and vital technical personnel—can be protected by fortifications.

Aircraft can be protected by

which will protect from many types of attack. Larger aircraft types tend to be based outside the operational theater.

Munition storage follows safety rules which use fortifications (bunkers and bunds) to provide protection against accident and chain reactions (sympathetic detonations). Weapons for rearming aircraft can be stored in small fortified expense stores closer to the aircraft. At Biên Hòa, South Vietnam, on the morning of May 16, 1965, as aircraft were being refueled and armed, a chain reaction explosion destroyed 13 aircraft, killed 34 personnel, and injured over 100; this, along with damage and losses of aircraft to enemy attack (by both infiltration and stand-off attacks), led to the construction of revetments and shelters to protect aircraft throughout South Vietnam.

Aircrew and ground personnel will need protection during enemy attacks and fortifications range from culvert section "duck and cover" shelters to permanent air raid shelters. Soft locations with high personnel densities such as accommodation and messing facilities can have limited protection by placing prefabricated concrete walls or barriers around them, examples of barriers are

in Iraq.

Fuel is volatile and has to comply with rules for storage which provide protection against accidents. Fuel in underground bulk fuel installations is well protected though valves and controls are vulnerable to enemy action. Above-ground tanks can be susceptible to attack.

Ground support equipment will need to be protected by fortifications to be usable after an enemy attack.

Permanent (concrete) guard fortifications are safer, stronger, last longer and are more cost-effective than sandbag fortifications. Prefabricated positions can be made from concrete culvert sections. The British Yarnold Bunker is made from sections of a concrete pipe.

Guard towers provide an increased field of view but a lower level of protection.

Dispersal and camouflage of assets can supplement fortifications against some forms of airfield attack.

Just as in colonial periods, comparatively obsolete fortifications are still used for low intensity conflicts. Such fortifications range in size from small patrol bases or

or even simple mud can provide protection against small arms and antitank weapons—although such fortifications are still vulnerable to mortar and artillery fire.

Forts

Forts in modern American usage often refer to space set aside by governments for a permanent military facility; these often do not have any actual fortifications, and can have specializations (military barracks, administration, medical facilities, or intelligence).

However, there are some modern fortifications that are referred to as forts. These are typically small semipermanent fortifications. In urban combat, they are built by upgrading existing structures such as houses or public buildings. In field warfare they are often log, sandbag or gabion type construction.

Such forts are typically only used in low-level conflicts, such as counterinsurgency conflicts or very low-level conventional conflicts, such as the Indonesia–Malaysia confrontation, which saw the use of log forts for use by forward platoons and companies. The reason for this is that static above-ground forts cannot survive modern direct or indirect fire weapons larger than mortars, RPGs and small arms.

Fortifications designed to keep the inhabitants of a facility in rather than attacker out can also be found, in

for example).

Field fortifications

References

•  This article incorporates text from a publication now in the public domain: Jackson, Louis Charles (1911). "Fortification and Siegecraft". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 10 (11th ed.). Cambridge University Press. pp. 679–725.

Bibliography

• July, Robert Pre-Colonial Africa, Charles Scribner, 1975.
• Murray, Nicholas. "The Development of Fortifications", The Encyclopedia of War, Gordon Martel (ed.). WileyBlackwell, 2011.
• Murray, Nicholas. The Rocky Road to the Great War: The Evolution of Trench Warfare to 1914. Potomac Books Inc. (an imprint of the University of Nebraska Press), 2013.
• Osadolor, Osarhieme Benson, "The Military System of Benin Kingdom 1440–1897", (UD), Hamburg University: 2001 copy.
• Thornton, John Kelly Warfare in Atlantic Africa, 1500–1800, Routledge: 1999,
  ISBN 1857283937
  .

External links

Look up fortification in Wiktionary, the free dictionary.

Wikimedia Commons has media related to Fortification.

• Fortress Study Group
• Military Architecture at the Wayback Machine (archived 5 December 2018)
• ICOFORT