A fortification (also called a fort, fortress, fastness, or stronghold) is a militaryconstruction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from Latinfortis ("strong") and facere ("to make").[1]
From very early history to modern times, defensive walls have often been necessary for cities to survive in an ever-changing world of invasion and conquest. Some settlements in the Indus Valley Civilization were the first small cities to be fortified. In ancient Greece, large stone walls had been built in Mycenaean Greece, such as the ancient site of Mycenae (known for the huge stone blocks of its 'cyclopean' walls). A Greek phrourion was a fortified collection of buildings used as a military garrison, and is the equivalent of the Romancastellum 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 semi-permanent 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.
Medieval-style fortifications were largely made obsolete by the arrival of cannons in the 14th century. Fortifications in the age of black powder evolved into much lower structures with greater use of ditches and earthramparts 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 explosive shells in the 19th century led to another stage in the evolution of fortification. 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. Steel-and-concrete fortifications were common during the 19th and early 20th centuries. The advances in modern warfare since World War I have made large-scale fortifications obsolete in most situations.
Many United States Army installations are known as forts, although they are not always fortified. During the pioneering era of North America, many outposts on the frontiers, even non-military outposts, were referred to generically as forts. Larger military installations may be called fortresses; smaller ones were once known as fortalices. The word fortification can refer to the practice of improving an area's defense with defensive works. City walls are fortifications but are not necessarily called fortresses.
The art of setting out a military camp or constructing a fortification traditionally has been called castrametation since the time of the Roman legions. Laying siege to a fortification and of destroying it is commonly called siegecraft or siege warfare and is formally known as poliorcetics. In some texts, this latter term also applies to the art of building a fortification.
Fortification is usually divided into two branches: permanent fortification and field fortification. Permanent fortifications are erected at leisure, with all the resources that a state can supply of constructive and mechanical skill, and are built of enduring materials. Field fortifications—for example breastworks—and often known as fieldworks or earthworks, are extemporized by troops in the field, perhaps assisted by such local labour and tools as may be procurable and with materials that do not require much preparation, such as soil, brushwood, and light timber,[2] or sandbags (see sangar). An example of field fortification[3] was the construction of Fort Necessity by George Washington in 1754.
There is also an intermediate branch known as semi-permanent fortification.[4] This is employed when in the course of a campaign it becomes desirable to protect some locality with the best imitation of permanent defences that can be made in a short time, ample resources and skilled civilian labour being available.[2] An example of this is the construction of Roman forts in England and in other Roman territories where camps were set up with the intention of staying for some time, but not permanently.
Castles are fortifications which are regarded as being distinct from the generic fort or fortress in that it describes a residence of a monarch or noble and commands a specific defensive territory. An example of this is the massive medieval castle of Carcassonne.
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".[5]
From very early history to modern times, walls have been a necessity for many cities. Amnya Fort in western Siberia has been described by archaeologists as one of the oldest known fortified settlements, as well as the northernmost Stone Age fort.[6] In Bulgaria, near the town of Provadia a walled fortified settlement today called Solnitsata starting from 4700 BC had a diameter of about 300 feet (91m), was home to 350 people living in two-storey houses, and was encircled by a fortified wall. The huge walls around the settlement, which were built very tall and with stone blocks which are 6 feet (1.8m) high and 4.5 feet (1.4m) thick, make it one of the earliest walled settlements in Europe[7][8] but it is younger than the walled town of Sesklo in Greece from 6800 BC.[9][10]
Uruk in ancient Sumer (Mesopotamia) is one of the world's oldest known walled cities. The Ancient Egyptians also built fortresses on the frontiers of the Nile Valley to protect against invaders from neighbouring territories, as well as circle-shaped mud brick walls around their cities. Many of the fortifications of the ancient world were built with mud brick, often leaving them no more than mounds of dirt for today's archaeologists. A massive prehistoric stone wall surrounded the ancient temple of Ness of Brodgar 3200 BC in Scotland. Named the "Great Wall of Brodgar" it was 4 metres (13ft) thick and 4 metres tall. The wall had some symbolic or ritualistic function.[11][12] The Assyrians deployed large labour forces to build new palaces, temples and defensive walls.[13]
Bronze Age Europe
Remains of a fortified village, Borġ in-Nadur, Malta. Borġ in-Nadur is a notable example of Bronze Age fortifications.
In Bronze AgeMalta, some settlements also began to be fortified. The most notable surviving example is Borġ in-Nadur, where a bastion built in around 1500 BC was found. Exceptions were few—notably, ancient Sparta and ancient Rome did not have walls for a long time, choosing to rely on their militaries for defence instead. Initially, these fortifications were simple constructions of wood and earth, which were later replaced by mixed constructions of stones piled on top of each other without mortar. In ancient Greece, large stone walls had been built in Mycenaean Greece, such as the ancient site of Mycenae (famous for the huge stone blocks of its 'cyclopean' walls). In classical era Greece, the city of Athens built two parallel stone walls, called the Long Walls, that reached their fortified seaport at Piraeus a few miles away.
In Central Europe, the Celts built large fortified settlements known as oppida, whose walls seem partially influenced by those built in the Mediterranean. The fortifications were continuously being expanded and improved. Around 600 BC, in Heuneburg, Germany, forts were constructed with a limestone foundation supported by a mudbrick wall approximately 4 metres tall, probably topped by a roofed walkway, thus reaching a total height of 6 metres. The wall was clad with lime plaster, regularly renewed. Towers protruded outwards from it.[14][15]
Reconstructed walls of Bibracte, a Gaulishoppidum, showing the construction technique known as 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 7.2km long walls. The oppidum of Bibracte is another example of a Gaulish fortified settlement.
The term casemate wall is used in the archaeology of Israel and the wider Near East, having the meaning of a double wall protecting a city[16] or fortress,[17] with transverse walls separating the space between the walls into chambers.[16] 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.[16] 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.[18] 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).[16] 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.[16][19] Casemate walls could surround an entire settlement, but most only protected part of it.[20] 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.[21]
Defensive wall of the ancient city of Dholavira, Gujarat 2600 BCE
A number of forts dating from the Later Stone Age to the British Raj are found in the mainland Indian subcontinent (modern day India, Pakistan, Bangladesh and Nepal). "Fort" is the word used in India for all old fortifications. Numerous Indus Valley Civilization sites exhibit evidence of fortifications. By about 3500 BC, hundreds of small farming villages dotted the Indus floodplain. Many of these settlements had fortifications and planned streets. The stone and mud brick houses of Kot Diji were clustered behind massive stone flood dykes and defensive walls, for neighbouring communities bickered constantly about the control of prime agricultural land.[22] The fortification varies by site. While Dholavira has stone-built fortification walls, Harrapa is fortified using baked bricks; sites such as Kalibangan exhibit mudbrick fortifications with bastions and Lothal has a quadrangular fortified layout. Evidence also suggested of fortifications in Mohenjo-daro. Even a small town—for instance, Kotada Bhadli, exhibiting sophisticated fortification-like bastions—shows that nearly all major and minor towns of the Indus Valley Civilization were fortified.[23] Forts also appeared in urban cities of the Gangetic valley during the second urbanisation period between 600 and 200 BC, and as many as 15 fortification sites have been identified by archaeologists throughout the Gangetic valley, such as Kaushambi, Mahasthangarh, Pataliputra, Mathura, Ahichchhatra, Rajgir, and Lauria Nandangarh. The earliest Mauryan period brick fortification occurs in one of the stupa mounds of Lauria Nandangarh, which is 1.6km in perimeter and oval in plan and encloses a habitation area.[24]Mundigak (c.2500 BC) in present-day south-east Afghanistan has defensive walls and square bastions of sun dried bricks.[25]
India currently has over 180 forts, with the state of Maharashtra alone having over 70 forts, which are also known as durg,[26][27][28] many of them built by Shivaji, founder of the Maratha Empire.
Forts in Sri Lanka date back thousands of years, with many being built by Sri Lankan kings. These include several walled cities. With the outset of colonial rule in the Indian Ocean, Sri Lanka was occupied by several major colonial empires that from time to time became the dominant power in the Indian Ocean. The colonists built several western-style forts, mostly in and around the coast of the island. The first to build colonial forts in Sri Lanka were the Portuguese; these forts were captured and later expanded by the Dutch. The British occupied these Dutch forts during the Napoleonic wars. Most of the colonial forts were garrisoned up until the early 20th century. The coastal forts had coastal artillery manned by the Ceylon Garrison Artillery 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 Sri Lankan Civil War; Jaffna fort, for example, came under siege several times.
The Great Wall of China near Jinshanling. The Great Wall was a series of fortifications built across the historical northern borders of China.
Large tempered earth (i.e. rammed earth) walls were built in ancient China since the Shang dynasty (c.1600–1050 BC); the capital at ancient Ao had enormous walls built in this fashion (see siege for more info). Although stone walls were built in China during the Warring States (481–221 BC), mass conversion to stone architecture did not begin in earnest until the Tang dynasty (618–907 AD). The Great Wall of China had been built since the Qin dynasty (221–207 BC), although its present form was mostly an engineering feat and remodelling of the Ming dynasty (1368–1644 AD).
During the Spanish Era several forts and outposts were built throughout the archipelago. Most notable is Intramuros, the old walled city of Manila located along the southern bank of the Pasig River.[29] The historic city was home to centuries-old churches, schools, convents, government buildings and residences, the best collection of Spanish colonial architecture before much of it was destroyed by the bombs of World War II. Of all the buildings within the 67-acre city, only one building, the San Agustin Church, survived the war.
The Ivatan people of the northern islands of Batanes built their so-called idjang on hills and elevated areas[30] 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.
An American flag raised at the Fort Santiago, 1898. Fort Santiago was a citadel that was a part of the Intramuros, a walled city within Manila.
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.[31]
The Muslim Filipinos of the south built strong fortresses called kota or moong to protect their communities. Usually, many of the occupants of these kotas are entire families rather than just warriors. Lords often had their own kotas to assert their right to rule, it served not only as a military installation but as a palace for the local Lord. It is said that at the height of the Maguindanao Sultanate's power, they blanketed the areas around Western Mindanao with kotas and other fortifications to block the Spanish advance into the region. These kotas were usually made of stone and bamboo or other light materials and surrounded by trench networks. As a result, some of these kotas were burned easily or destroyed. With further Spanish campaigns in the region, the sultanate was subdued and a majority of kotas dismantled or destroyed. kotas were not only used by the Muslims as defense against Spaniards and other foreigners, renegades and rebels also built fortifications in defiance of other chiefs in the area.[citation needed] During the American occupation, rebels built strongholds and the datus, rajahs, or sultans often built and reinforced their kotas in a desperate bid to maintain rule over their subjects and their land.[32] Many of these forts were also destroyed by American expeditions, as a result, very very few kotas still stand to this day.
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"[33]
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.
Map of the defences available during the Battle of the Trench, 627. Muslim defenders repelled the Confederates using Medina's natural fortifications and makeshift trenches.
During Muhammad's era in Arabia, many tribes made use of fortifications. In the Battle of the Trench, the largely outnumbered defenders of Medina, mainly Muslims led by Islamic prophet Muhammad, dug a trench, which together with Medina's natural fortifications, rendered the confederate cavalry (consisting of horses and camels) useless, locking the two sides in a stalemate. Hoping to make several attacks at once, the confederates persuaded the Medina-allied Banu Qurayza to attack the city from the south. However, Muhammad's diplomacy derailed the negotiations, and broke up the confederacy against him. The well-organized defenders, the sinking of confederate morale, and poor weather conditions caused the siege to end in a fiasco.[34]
During the Siege of Ta'if in January 630,[35] Muhammad ordered his followers to attack enemies who fled from the Battle of Hunayn and sought refuge in the fortress of Taif.[36]
The entire city of Kerma in Nubia (present day Sudan) was encompassed by fortified walls surrounded by a ditch. Archaeology has revealed various Bronze Age bastions and foundations constructed of stone together with either baked or unfired brick.[37]
The walls of Benin are described as the world's second longest man-made structure, as well as the most extensive earthwork in the world, by the Guinness Book of Records, 1974.[38][39] The walls may have been constructed between the thirteenth and mid-fifteenth century CE[40] or, during the first millennium CE.[40][41] Strong citadels were also built other in areas of Africa. Yorubaland for example had several sites surrounded by the full range of earthworks and ramparts seen elsewhere, and sited on ground. This improved defensive potential—such as hills and ridges. Yoruba fortifications were often protected with a double wall of trenches and ramparts, and in the Congo forests concealed ditches and paths, along with the main works, often bristled with rows of sharpened stakes. Inner defenses were laid out to blunt an enemy penetration with a maze of defensive walls allowing for entrapment and crossfire on opposing forces.[42]
A military tactic of the Ashanti was to create powerful log stockades at key points. This was employed in later wars against the British to block British advances. Some of these fortifications were over a hundred yards long, with heavy parallel tree trunks. They were impervious to destruction by artillery fire. Behind these stockades, numerous Ashanti soldiers were mobilized to check enemy movement. While formidable in construction, many of these strongpoints failed because Ashanti guns, gunpowder and bullets were poor, and provided little sustained killing power in defense. Time and time again British troops overcame or bypassed the stockades by mounting old-fashioned bayonet charges, after laying down some covering fire.[43]
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.[44]
Medieval defensive walls and towers in Szprotawa, Poland, made of field stone and bog iron.
Roman forts and hill forts were the main antecedents of castles in Europe, which emerged in the 9th century in the Carolingian Empire. The Early Middle Ages saw the creation of some towns built around castles. These cities were only rarely protected by simple stone walls and more usually by a combination of both walls and ditches. 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 centres was an important means of territorial expansion and many cities, especially in eastern Europe, were founded precisely for this purpose during the period of Eastern Colonisation. These cities are easy to recognise due to their regular layout and large market spaces. The fortifications of these settlements were continuously improved to reflect the current level of military development. During the Renaissance era, the Venetian Republic raised great walls around cities, and the finest examples, among others, are in Nicosia (Cyprus), Rocca di Manerba del Garda (Lombardy), and Palmanova (Italy), or Dubrovnik (Croatia), which proved to be futile against attacks but still stand to this day. Unlike the Venetians, the Ottomans used to build smaller fortifications but in greater numbers, and only rarely fortified entire settlements such as Počitelj, Vratnik, and Jajce in Bosnia.
Medieval-style fortifications were largely made obsolete by the arrival of cannons on the 14th century battlefield. Fortifications in the age of black powder evolved into much lower structures with greater use of ditches and earthramparts 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.
Table of a typical bastion fort, 1728. The development of bastion forts resulted from the increased use of cannons and firearms in the 14th century.
The evolution of this new style of fortification can be seen in transitional forts such as Sarzanello[45] 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.[46] 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.
During the 18th century, it was found that the continuous enceinte, or main defensive enclosure of a bastion fortress, could not be made large enough to accommodate the enormous field armies which were increasingly being employed in Europe; neither could the defences be constructed far enough away from the fortress town to protect the inhabitants from bombardment by the besiegers, the range of whose guns was steadily increasing as better manufactured weapons were introduced. Threfore, since refortifying the Prussian fortress cities of Koblenz and Cologne after 1815, the principle of the ring fortress or girdle fortress was used: forts, each several hundred metres out from the original enceinte, were carefully sited so as to make best use of the terrain and to be capable of mutual support with the neighbouring forts.[47] Gone were citadels surrounding towns: forts were to be moved to the outside of the cities some 12km to keep the enemy at a distance so their artillery could not bombard the city center. 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 explosive shells in the 19th century led to yet another stage in the evolution of fortification. 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.
The ditch and counter scarp of Fort Delimara. Built in 1878, Delimara was built as a typical polygonal fort ditches and counter scarps made to be very deep, vertically sided, and cut directly into the rocks.
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 counter scarp. 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 blockhouses 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 caponiers 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.
The tunnels of Fort de Mutzig, German fortifications built in 1893. By the 19th century, tunnels were used to connect blockhouses and firing points in the ditch to the fort.
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.
20th and 21st centuries
Gun emplacement in Fort Campbell, built in the 1930s. Due to the threat of aerial warfare, the buildings were placed at a distance from each other, making it difficult to find from the air.
Steel-and-concrete fortifications were common during the 19th and early 20th centuries. However, the advances in modern warfare since World War I have made large-scale fortifications obsolete in most situations. In the 1930s and 1940s, some fortifications were built with designs taking into consideration the new threat of aerial warfare, such as Fort Campbell in Malta.[48] Despite this, only underground bunkers are still able to provide some protection in modern wars. Many historical fortifications were demolished during the modern age, but a considerable number survive as popular tourist destinations and prominent local landmarks 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.[49]
A GBU-242,000lb (910kg) bomb hits the ground. The development of bunker busters, bombs designed to penetrate hardened targets buried underground, led to a decline in the use of fortifications.
Instead field fortification rose to dominate defensive action. Unlike the trench warfare which dominated World War I, these defences 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 re-established relatively quickly. Instead of a supposedly impenetrable defensive line, such fortifications emphasized defence in depth, so that as defenders were forced to pull back or were overrun, the lines of defenders behind them could take over the defence.
Because the mobile offensives practised by both sides usually focused on avoiding the strongest points of a defensive line, these defences were usually relatively thin and spread along the length of a line. The defence 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 defences consisted primarily of infantry and anti-tank guns. Defending tanks and tank destroyers would be concentrated in mobile brigades 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 defences, 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.
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 Battle of the Hurtgen Forest 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, intercontinental ballistic missiles capable of reaching much of the way around the world were developed, so speed became an essential characteristic of the strongest militaries and defenses. Missile silos were developed, so missiles could be fired from the middle of a country and hit cities and targets in another country, and airplanes (and aircraft carriers) became major defenses and offensive weapons (leading to an expansion of the use of airports and airstrips as fortifications). Mobile defenses could be had underwater, too, in the form of ballistic missile submarines capable of firing submarine launched ballistic missiles. Some bunkers in the mid to late 20th century came to be buried deep inside mountains and prominent rocks, such as Gibraltar and the Cheyenne Mountain Complex. On the ground itself, minefields have been used as hidden defences 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.
Military airfields
Military airfields offer a fixed "target rich" environment for even relatively small enemy forces, using hit-and-run tactics 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.
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 Bien Hoa South Vietnam on the morning of 16 May 1965, as aircraft were being re-fuelled 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 Jersey Barriers, T Barriers or Splinter Protection Units (SPUs). Older fortification may prove useful such as the old 'Yugo' pyramid shelters built in the 1980s which were used by US personnel on 8 Jan 2020 when Iran fired 11 ballistic missiles at Ayn al-Asad Airbase 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.
Counter-insurgency
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 forward operating bases up to huge airbases such as Camp Bastion/Leatherneck in Afghanistan. Much like in the 18th and 19th century, because the enemy is not a powerful military force with the heavy weaponry required to destroy fortifications, walls of gabion, sandbag or even simple mud can provide protection against small arms and anti-tank weapons—although such fortifications are still vulnerable to mortar and artillery fire.
Forts
The Ozama Fortress in Santo Domingo, Dominican Republic is recognized by UNESCO for being the oldest military construction of European origin in the Americas.
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 semi-permanent 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.
Prisons and others
Fortifications designed to keep the inhabitants of a facility in rather than attacker out can also be found, in prisons, concentration camps, and other such facilities. Those are covered in other articles, as most prisons and concentration camps are not primarily military forts (although forts, camps, and garrison towns have been used as prisons and/or concentration camps; such as Theresienstadt, Guantanamo Bay detention camp and the Tower of London for example).
↑ A. Wade, Dale. "THE USE OF FENCES FOR PREDATOR DAMAGE CONTROL". University of Nebraska - Lincoln. Wade, Dale A., "THE USE OF FENCES FOR PREDATOR DAMAGE CONTROL" (1982). Proceedings of the Tenth Vertebrate Pest Conference (1982). 47. Retrieved 19 September 2024.
↑ Stearns, Peter N.; Langer, William Leonard (2001). The Encyclopedia of World History: ancient, medieval, and modern, chronologically arranged. Houghton Mifflin Books. p.17. ISBN0-395-65237-5.
↑ Barba, Federica (2004). "The Fortified Cities of the Ganges Plain in the First Millennium B.C.". East and West. 54 (1/4): 223–250. JSTOR29757611.
↑ Fletcher, Banister; Cruickshank, Dan (1996). Sir Banister Fletcher's A History of Architecture. Architectural Press. p.100. ISBN0-7506-2267-9.
↑ Durga is the Sanskrit word for "inaccessible place", hence "fort"
1 2 Nossov, Konstantin (2012). Indian Castles 1206–1526: The Rise and Fall of the Delhi Sultanate (seconded.). Oxford: Osprey Publishing. p.8. ISBN978-1-78096-985-5.
↑ Muir, William. The life of Mahomet and history of Islam to the era of the Hegira. Vol.4. p.142.
↑ Bianchi, Robert Steven (2004). Daily Life of the Nubians. Greenwood Publishing Group. p.83. ISBN978-0-313-32501-4.
↑ Gates, Henry Louis; Appiah, Anthony (1999). Africana: The Encyclopedia of the African and African American Experience. Basic Civitas Books. p.97. ISBN0195170555.
1 2 Ogundiran, Akinwumi (June 2005). "Four Millennia of Cultural History in Nigeria (ca. 2000 B.C.–A.D. 1900): Archaeological Perspectives". Journal of World Prehistory. 19 (2): 133–168. doi:10.1007/s10963-006-9003-y. S2CID144422848.
↑ Medieval Town of Rhodes – Restoration Works (1985–2000) – Part One. Rhodes: Ministry of Culture – Works supervision committee for the monuments of the medieval town of Rhodes. 2001.
↑ Mifsud, Simon (14 September 2012). "Fort Campbell". MilitaryArchitecture.com. Archived from the original on 15 November 2015. Retrieved 15 March 2015.
A citadel is the most fortified area of a town or city. It may be a castle, fortress, or fortified center. The term is a diminutive of city, meaning "little city", because it is a smaller part of the city of which it is the defensive core.
A siege is a military blockade of a city, or fortress, with the intent of conquering by attrition, or by well-prepared assault. Siege warfare is a form of constant, low-intensity conflict characterized by one party holding a strong, static, defensive position. Consequently, an opportunity for negotiation between combatants is common, as proximity and fluctuating advantage can encourage diplomacy.
A defensive wall is a fortification usually used to protect a city, town or other settlement from potential aggressors. The walls can range from simple palisades or earthworks to extensive military fortifications such as curtain walls with towers, bastions and gates for access to the city. From ancient to modern times, they were used to enclose settlements. Generally, these are referred to as city walls or town walls, although there were also walls, such as the Great Wall of China, Walls of Benin, Hadrian's Wall, Anastasian Wall, and the Atlantic Wall, which extended far beyond the borders of a city and were used to enclose regions or mark territorial boundaries. In mountainous terrain, defensive walls such as letzis were used in combination with castles to seal valleys from potential attack. Beyond their defensive utility, many walls also had important symbolic functions – representing the status and independence of the communities they embraced.
A hillfort is a type of fortified refuge or defended settlement located to exploit a rise in elevation for defensive advantage. They are typical of the late European Bronze Age and Iron Age. Some were used in the post-Roman period. The fortification usually follows the contours of a hill and consists of one or more lines of earthworks or stone ramparts, with stockades or defensive walls, and external ditches. If enemies were approaching, the civilians would spot them from a distance.
A siege engine is a device that is designed to break or circumvent heavy castle doors, thick city walls and other fortifications in siege warfare. Some are immobile, constructed in place to attack enemy fortifications from a distance, while others have wheels to enable advancing up to the enemy fortification. There are many distinct types, such as siege towers that allow foot soldiers to scale walls and attack the defenders, battering rams that damage walls or gates, and large ranged weapons that attack from a distance by launching projectiles. Some complex siege engines were combinations of these types.
A bastion is a structure projecting outward from the curtain wall of a fortification, most commonly angular in shape and positioned at the corners of the fort. The fully developed bastion consists of two faces and two flanks, with fire from the flanks being able to protect the curtain wall and the adjacent bastions. Compared with the medieval fortified towers they replaced, bastion fortifications offered a greater degree of passive resistance and more scope for ranged defence in the age of gunpowder artillery. As military architecture, the bastion is one element in the style of fortification dominant from the mid 16th to mid 19th centuries.
The National Redoubt was a strategic defensive belt of fortifications built in Belgium. The National redoubt was the infrastructural cornerstone of Belgian defensive strategy from 1890–1940.
The Western Heights of Dover is a series of forts and ditches in Dover, England. They were created in the 18th and 19th centuries to augment the existing defences and protect the key port of Dover from both seaward and landward attack; by the start of the 20th century Dover Western Heights was collectively reputed to be the 'strongest and most elaborate' fortification in the country. The Army finally withdrew from the Heights in 1956–61; they are now a local nature reserve.
A casemate is a fortified gun emplacement or armoured structure from which guns are fired, in a fortification, warship, or armoured fighting vehicle.
A bastion fort or trace italienne is a fortification in a style that evolved during the early modern period of gunpowder when the cannon came to dominate the battlefield. It was first seen in the mid-fifteenth century in Italy. Some types, especially when combined with ravelins and other outworks, resembled the related star fort of the same era.
Sapping is a term used in siege operations to describe the digging of a covered trench to approach a besieged place without danger from the enemy's fire. The purpose of the sap is usually to advance a besieging army's position towards an attacked fortification. It is excavated by specialised military units, whose members are often called sappers.
The Séré de Rivières system was an ensemble of fortifications built from 1874 along the frontiers, ridges and coasts of France. The fortifications were named after their architect, Brigadier-General Raymond Adolphe Séré de Rivières. The fortresses were obsolescent by 1914 but were used during the First World War.
The fortified position of Liège was established after the First World War by Belgium to block the traditional invasion corridor through Belgium between Germany and France. In the First World War the Belgian Army held up the Germans for a week at Liège, delaying the German invasion of France, caused Belgium to consider a similar defensive strategy. Belgium rebuilt the Liège fortifications and extended them onto the Pays de Herve closer to Germany, using the most advanced fortification technology available.
A Carnot wall is a type of loop-holed wall built in the ditch of a fort or redoubt. It takes its name from the French mathematician, politician, and military engineer Lazare Carnot. Such walls were introduced into the design of fortifications from the early nineteenth century. As conceived by Carnot, they formed part of an innovative but controversial system of fortification intended to defend against artillery and infantry attack. Carnot walls were employed, together with other elements of Carnot's system, in continental Europe in the years after the final defeat of Napoleon in 1815, especially by the Prussians, other Germans and Austrians. Their adoption was initially resisted by the French themselves and by the British.
The Gibraltar peninsula, located at the far southern end of Iberia, has great strategic importance as a result of its position by the Strait of Gibraltar where the Mediterranean Sea meets the Atlantic Ocean. It has repeatedly been contested between European and North African powers and has endured fourteen sieges since it was first settled in the 11th century. The peninsula's occupants – Moors, Spanish, and British – have built successive layers of fortifications and defences including walls, bastions, casemates, gun batteries, magazines, tunnels and galleries. At their peak in 1865, the fortifications housed around 681 guns mounted in 110 batteries and positions, guarding all land and sea approaches to Gibraltar. The fortifications continued to be in military use until as late as the 1970s and by the time tunnelling ceased in the late 1960s, over 34 miles (55 km) of galleries had been dug in an area of only 2.6 square miles (6.7 km2).
The fortifications of Malta consist of a number of walled cities, citadels, forts, towers, batteries, redoubts, entrenchments and pillboxes. The fortifications were built over hundreds of years, from around 1450 BC to the mid-20th century, and they are a result of the Maltese islands' strategic position and natural harbours, which have made them very desirable for various powers.
In fortification architecture, a rampart is a length of embankment or wall forming part of the defensive boundary of a castle, hillfort, settlement or other fortified site. It is usually broad-topped and made of excavated earth and/or masonry.
The fortifications of Mdina are a series of defensive walls which surround Mdina, the former capital city of Malta from antiquity to the medieval period. The city was founded as Maleth by the Phoenicians in around the 8th century BC, and it later became part of the Roman Empire under the name Melite. The ancient city was surrounded by walls, but very few remains of these have survived.
A polygonal fort is a type of fortification originating in France in the late 18th century and fully developed in Germany in the first half of the 19th century. Unlike earlier forts, polygonal forts had no bastions, which had proved to be vulnerable. As part of ring fortresses, polygonal forts were generally arranged in a ring around the place they were intended to protect, so that each fort could support its neighbours. The concept of the polygonal fort proved to be adaptable to improvements in the artillery which might be used against them, and they continued to be built and rebuilt well into the 20th century.
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, ISBN1857283937.
External links
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