![Aerial photo of the Valletta City Gate](https://upload.wikimedia.org/wikipedia/commons/9/9d/Aerial_photo_of_the_Valletta_City_Gate.jpg)
A fortification is a
military
A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...
construction
Construction is a general term meaning the art and science to form Physical object, objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Pr ...
or
building
A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and fu ...
designed for the defense of territories in
war
War is an intense armed conflict between states, governments, societies, or paramilitary groups such as mercenaries, insurgents, and militias. It is generally characterized by extreme violence, destruction, and mortality, using regular o ...
fare, and is also used to establish rule in a region during peacetime. The term is derived from
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''fortis'' ("strong") and ''facere'' ("to make").
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
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean Sea, Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, classical antiquity ( AD 600), th ...
, large stone walls had been built in
Mycenaean Greece, such as the ancient site of
Mycenae
Mycenae ( ; grc, Μυκῆναι or , ''Mykē̂nai'' or ''Mykḗnē'') is an archaeological site near Mykines in Argolis, north-eastern Peloponnese, Greece. It is located about south-west of Athens; north of Argos; and south of Corinth. ...
(famous for the huge stone blocks of its '
cyclopean
Cyclopean masonry is a type of stonework found in Mycenaean architecture, built with massive limestone boulders, roughly fitted together with minimal clearance between adjacent stones and with clay mortar or no use of mortar. The boulders typic ...
' walls). A Greek ''
phrourion'' was a fortified collection of buildings used as a military
garrison, and is the equivalent of the
Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*'' Epistle to the Romans'', shortened to ''Romans'', a lette ...
castellum or
English
English usually refers to:
* English language
* English people
English may also refer to:
Peoples, culture, and language
* ''English'', an adjective for something of, from, or related to England
** English national ide ...
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 legion
The Roman legion ( la, legiō, ) was the largest military unit of the Roman army, composed of 5,200 infantry and 300 equites (cavalry) in the period of the Roman Republic (509 BC–27 BC) and of 5,600 infantry and 200 auxilia in the period o ...
s. Fortification is usually divided into two branches: permanent fortification and field fortification. There is also an intermediate branch known as semi-permanent fortification.
Castles are fortifications which are regarded as being distinct from the generic fort or fortress in that they are a residence of a
monarch
A monarch is a head of stateWebster's II New College DictionarMonarch Houghton Mifflin. Boston. 2001. p. 707. for life or until abdication, and therefore the head of state of a monarchy. A monarch may exercise the highest authority and power i ...
or
noble
A noble is a member of the nobility.
Noble may also refer to:
Places Antarctica
* Noble Glacier, King George Island
* Noble Nunatak, Marie Byrd Land
* Noble Peak, Wiencke Island
* Noble Rocks, Graham Land
Australia
* Noble Island, Gr ...
and command a specific defensive territory.
Roman forts
In the Roman Republic and the Roman Empire, the Latin word ''castrum'', plural ''castra'', was a military-related term.
In Latin usage, the singular form ''castrum'' meant 'fort', while the plural form ''castra'' meant 'camp'. The singular and ...
and
hill fort
A hillfort is a type of earthwork used as a fortified refuge or defended settlement, located to exploit a rise in elevation for defensive advantage. They are typically European and of the Bronze Age or Iron Age. Some were used in the post-Roma ...
s were the main antecedents of castles in
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
, which emerged in the 9th century in the
Carolingian Empire
The Carolingian Empire (800–888) was a large Frankish-dominated empire in western and central Europe during the Early Middle Ages. It was ruled by the Carolingian dynasty, which had ruled as kings of the Franks since 751 and as kings of the ...
. The
Early Middle Ages
The Early Middle Ages (or early medieval period), sometimes controversially referred to as the Dark Ages, is typically regarded by historians as lasting from the late 5th or early 6th century to the 10th century. They marked the start of the Mi ...
saw the creation of some towns built around castles.
Medieval-style fortifications were largely made obsolete by the arrival of
cannon
A cannon is a large- caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder ...
s in the 14th century. Fortifications in the age of
black powder evolved into much lower structures with greater use of
ditches
A ditch is a small to moderate divot created to channel water. A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. Ditches ar ...
and
earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
ramparts 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 shell
A shell, in a military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military context. Modern usage ...
s 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 explosive, 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
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
fortifications were common during the 19th and early 20th centuries. The advances in modern warfare since
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
have made large-scale fortifications
obsolete in most situations.
Nomenclature
![Imperial Encyclopaedia - Military Administration - pic523](https://upload.wikimedia.org/wikipedia/commons/0/01/Imperial_Encyclopaedia_-_Military_Administration_-_pic523.png)
Many United States Army installations are known as ''forts'', although they are not always fortified. Indeed, 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 also refer to the practice of improving an area's defense with defensive works. City
walls
Walls may refer to:
*The plural of wall, a structure
*Walls (surname), a list of notable people with the surname
Places
* Walls, Louisiana, United States
* Walls, Mississippi, United States
* Walls, Ontario, neighborhood in Perry, Ontario, C ...
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 legion
The Roman legion ( la, legiō, ) was the largest military unit of the Roman army, composed of 5,200 infantry and 300 equites (cavalry) in the period of the Roman Republic (509 BC–27 BC) and of 5,600 infantry and 200 auxilia in the period o ...
s. The art/science of laying
siege
A siege is a military blockade of a city, or fortress, with the intent of conquering by attrition, or a well-prepared assault. This derives from la, sedere, lit=to sit. Siege warfare is a form of constant, low-intensity conflict characteriz ...
to a fortification and of destroying it is commonly called ''
siegecraft
A siege is a military blockade of a city, or fortress, with the intent of conquering by attrition, or a well-prepared assault. This derives from la, sedere, lit=to sit. Siege warfare is a form of constant, low-intensity conflict characterize ...
'' or ''siege warfare'' and is formally known as ''
poliorcetics
A siege is a military blockade of a city, or fortress, with the intent of conquering by attrition, or a well-prepared assault. This derives from la, sedere, lit=to sit. Siege warfare is a form of constant, low-intensity conflict characterize ...
''. 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
Mechanical may refer to:
Machine
* Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement
* Mechanical calculator, a device used to perform the basic operations of ...
skill, and are built of enduring materials. Field fortifications—for example
breastworks
A breastwork is a temporary fortification, often an earthwork thrown up to breast height to provide protection to defenders firing over it from a standing position. A more permanent structure, normally in stone, would be described as a parapet o ...
—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
earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, brushwood and light
timber
Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, w ...
, or sandbags (see
sangar). An example of field fortification was the construction of
Fort Necessity
Fort Necessity National Battlefield is a National Battlefield in Fayette County, Pennsylvania, United States, which preserves the site of the Battle of Fort Necessity. The battle, which took place on July 3, 1754, was an early battle of the ...
by George Washington in 1754.
There is also an intermediate branch known as ''semi-permanent fortification''. 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. 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
A monarch is a head of stateWebster's II New College DictionarMonarch Houghton Mifflin. Boston. 2001. p. 707. for life or until abdication, and therefore the head of state of a monarchy. A monarch may exercise the highest authority and power i ...
or
noble
A noble is a member of the nobility.
Noble may also refer to:
Places Antarctica
* Noble Glacier, King George Island
* Noble Nunatak, Marie Byrd Land
* Noble Peak, Wiencke Island
* Noble Rocks, Graham Land
Australia
* Noble Island, Gr ...
and commands a specific defensive territory. An example of this is the massive medieval castle of
Carcassonne
Carcassonne (, also , , ; ; la, Carcaso) is a French fortified city in the department of Aude, in the region of Occitanie. It is the prefecture of the department.
Inhabited since the Neolithic, Carcassonne is located in the plain of the Au ...
.
History
Neolithic Europe
From very early history to modern times,
walls
Walls may refer to:
*The plural of wall, a structure
*Walls (surname), a list of notable people with the surname
Places
* Walls, Louisiana, United States
* Walls, Mississippi, United States
* Walls, Ontario, neighborhood in Perry, Ontario, C ...
have been a necessity for many cities. In Bulgaria, near the town of
Provadia
Provadia ( bg, Провадия ) is a town in northeastern Bulgaria, part of Varna Province, located in a deep karst gorge (Provadia syncline) along the Provadiya River not far from the Bulgarian Black Sea Coast. It is the administrative centre ...
a walled fortified settlement today called
Solnitsata
Solnitsata ( bg, Солницата, "The Saltworks") was a prehistoric town located in present-day Bulgaria, near the modern city of Provadia. Believed by archaeologists to be the oldest town in Europe, Solnitsata was a fortified stone settlement ...
starting from 4700 BC had a diameter of about , 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 high and thick, make it one of the earliest walled settlements in Europe but it is younger than the walled town of
Sesklo
Sesklo ( el, Σέσκλο; rup, Seshklu) is a village in Greece that is located near Volos, a city located within the municipality of Aisonia. The municipality is located within the regional unit of Magnesia that is located within the admini ...
in Greece from 6800 BC.
Uruk
Uruk, also known as Warka or Warkah, was an ancient city of Sumer (and later of Babylonia) situated east of the present bed of the Euphrates River on the dried-up ancient channel of the Euphrates east of modern Samawah, Al-Muthannā, Iraq.Harm ...
in ancient
Sumer (
Mesopotamia
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the ...
) is one of the world's oldest known
walled cities
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 with towers, bastions and gates ...
. 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
The Ness of Brodgar is an archaeological site covering between the Ring of Brodgar and the Stones of Stenness in the Heart of Neolithic Orkney World Heritage Site in Orkney, Scotland. Excavations at the site began in 2003. The site has provided ...
3200 BC in
Scotland
Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...
. Named the "Great Wall of Brodgar" it was thick and 4 metres tall. The wall had some symbolic or ritualistic function. The
Assyrians deployed large labour forces to build new
palaces
A palace is a grand residence, especially a royal residence, or the home of a head of state or some other high-ranking dignitary, such as a bishop or archbishop. The word is derived from the Latin name palātium, for Palatine Hill in Rome whic ...
, temples and defensive walls.
Neolithic Indus Valley
Some settlements in the
Indus Valley civilization were also fortified. 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
The ancient site at Kot Diji ( sd, ڪوٽ ڏیجي; ur, کوٹ ڈیجی) was the forerunner of the Indus Civilization. The occupation of this site is attested already at 3300 BCE. The remains consist of two parts; the citadel area on high ground ...
were clustered behind massive stone flood dykes and defensive walls, for neighbouring communities bickered constantly about the control of prime agricultural land.
Mundigak
Mundigak ( ps, منډیګک) is an archaeological site in Kandahar province in Afghanistan. During the Bronze Age, it was a center of the Helmand culture. It is situated approximately northwest of Kandahar near Shāh Maqsūd, on the upper draina ...
(c. 2500 BC) in present-day south-east
Afghanistan
Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...
has defensive walls and square
bastions of sun dried bricks. The entire city of
Kerma
Kerma was the capital city of the Kerma culture, which was located in present-day Sudan at least 5,500 years ago. Kerma is one of the largest archaeological sites in ancient Nubia. It has produced decades of extensive excavations and research, i ...
in
Nubia
Nubia () (Nobiin: Nobīn, ) is a region along the Nile river encompassing the area between the first cataract of the Nile (just south of Aswan in southern Egypt) and the confluence of the Blue and White Niles (in Khartoum in central Sudan), or ...
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.
Bronze Age Europe
In
Bronze Age
The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second prin ...
Malta
Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...
, some settlements also began to be fortified. The most notable surviving example is
Borġ in-Nadur
Borġ in-Nadur is an archaeological site located in open fields overlooking St George's Bay, near Birżebbuġa, Malta. It is occupied by a Tarxien phase megalithic temple as well as the remains of a Bronze Age village which includes the earlies ...
, where a bastion built in around 1500 BC was found.
Babylon was one of the most famous cities of the ancient world, especially as a result of the building program of
Nebuchadnezzar, who expanded the walls and built the
Ishtar Gate
The Ishtar Gate was the eighth gate to the inner city of Babylon (in the area of present-day Hillah, Babil Governorate, Iraq). It was constructed circa 575 BCE by order of King Nebuchadnezzar II on the north side of the city. It was pa ...
. Exceptions were few—notably, ancient
Sparta
Sparta ( Doric Greek: Σπάρτα, ''Spártā''; Attic Greek: Σπάρτη, ''Spártē'') was a prominent city-state in Laconia, in ancient Greece. In antiquity, the city-state was known as Lacedaemon (, ), while the name Sparta referre ...
and ancient
Rome
, established_title = Founded
, established_date = 753 BC
, founder = King Romulus (legendary)
, image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg
, map_caption ...
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
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean Sea, Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, classical antiquity ( AD 600), th ...
, large stone walls had been built in
Mycenaean Greece, such as the ancient site of
Mycenae
Mycenae ( ; grc, Μυκῆναι or , ''Mykē̂nai'' or ''Mykḗnē'') is an archaeological site near Mykines in Argolis, north-eastern Peloponnese, Greece. It is located about south-west of Athens; north of Argos; and south of Corinth. ...
(famous for the huge stone blocks of its '
cyclopean
Cyclopean masonry is a type of stonework found in Mycenaean architecture, built with massive limestone boulders, roughly fitted together with minimal clearance between adjacent stones and with clay mortar or no use of mortar. The boulders typic ...
' walls). In
classical era
Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history between the 8th century BC and the 5th century AD centred on the Mediterranean Sea, comprising the interlocking civilizations of ...
Greece
Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders ...
, the city of
Athens
Athens ( ; el, Αθήνα, Athína ; grc, Ἀθῆναι, Athênai (pl.) ) is both the capital and largest city of Greece. With a population close to four million, it is also the seventh largest city in the European Union. Athens dominates ...
built two parallel stone walls, called the
Long Walls
Although long walls were built at several locations in ancient Greece, notably Corinth and Megara, the term Long Walls ( grc, Μακρὰ Τείχη ) generally refers to the walls that connected Athens main city to its ports at Piraeus and Phal ...
, that reached their fortified seaport at
Piraeus
Piraeus ( ; el, Πειραιάς ; grc, Πειραιεύς ) is a port city within the Athens urban area ("Greater Athens"), in the Attica region of Greece. It is located southwest of Athens' city centre, along the east coast of the Saron ...
a few miles away.
In
Central Europe
Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the a ...
, the
Celts
The Celts (, see pronunciation for different usages) or Celtic peoples () are. "CELTS location: Greater Europe time period: Second millennium B.C.E. to present ancestry: Celtic a collection of Indo-European peoples. "The Celts, an ancien ...
built large fortified settlements known as
oppida
An ''oppidum'' (plural ''oppida'') is a large fortified Iron Age settlement or town. ''Oppida'' are primarily associated with the Celtic late La Tène culture, emerging during the 2nd and 1st centuries BC, spread across Europe, stretch ...
, whose walls seem partially influenced by those built in the
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western Europe, Western and Southern Europe and Anatolia, on the south by North Africa ...
. The fortifications were continuously being expanded and improved. Around 600 BC, in
Heuneburg
The Heuneburg is a prehistoric hillfort by the river Danube in Hundersingen near Herbertingen, between Ulm and Sigmaringen, Baden-Württemberg, in the south of Germany, close to the modern borders with Switzerland and Austria. It is considered ...
, 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.
![Bibracte Porte Rebout](https://upload.wikimedia.org/wikipedia/commons/b/bb/Bibracte_Porte_Rebout.jpg)
The
Oppidum of Manching
The Oppidum of Manching (german: Oppidum von Manching) was a large Celtic proto-urban or city-like settlement at modern-day Manching, near Ingolstadt, in Bavaria, Germany. The Iron Age town (or oppidum) was founded in the 3rd century BC and exis ...
(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
Bibracte, a Gallic ''oppidum'' or fortified settlement, was the capital of the Aedui and one of the most important hillforts in Gaul. It was situated near modern Autun in Burgundy, France. The material culture of the Aedui corresponded to the ...
is another example of a Gaulish fortified settlement.
Bronze and Iron Age Near East
Ancient Rome
The
Mura aureliane are a line of
city wall
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 with towers, bastions and gates ...
s built between 271 AD and 275 AD in
Rome
, established_title = Founded
, established_date = 753 BC
, founder = King Romulus (legendary)
, image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg
, map_caption ...
,
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
, during the reign of the
Roman Emperors
Aurelian and
Probus. The walls enclosed all the
seven hills of Rome
The seven hills of Rome ( la, Septem colles/montes Romae, it, Sette colli di Roma ) east of the river Tiber form the geographical heart of Rome, within the walls of the city.
Hills
The seven hills are:
* Aventine Hill (Latin: ''Collis Aventi ...
plus the
Campus Martius
The Campus Martius (Latin for the "Field of Mars", Italian ''Campo Marzio'') was a publicly owned area of ancient Rome about in extent. In the Middle Ages, it was the most populous area of Rome. The IV rione of Rome, Campo Marzio, which cove ...
and, on the right bank of the
Tiber
The Tiber ( ; it, Tevere ; la, Tiberis) is the third-longest List of rivers of Italy, river in Italy and the longest in Central Italy, rising in the Apennine Mountains in Emilia-Romagna and flowing through Tuscany, Umbria, and Lazio, where ...
, the
Trastevere district. The river banks within the city limits appear to have been left unfortified, although they were fortified along the Campus Martius. The full circuit ran for surrounding an area of . The walls were constructed in brick-faced concrete, thick and high, with a square tower every 100 Roman feet (). In the 5th century, remodelling doubled the height of the walls to . By 500 AD, the circuit possessed 383 towers, 7,020
crenellation
A battlement in defensive architecture, such as that of city walls or castles, comprises a parapet (i.e., a defensive low wall between chest-height and head-height), in which gaps or indentations, which are often rectangular, occur at interva ...
s, 18 main gates, 5
postern gates, 116
latrine
A latrine is a toilet or an even simpler facility that is used as a toilet within a sanitation system. For example, it can be a communal trench in the earth in a camp to be used as emergency sanitation, a hole in the ground ( pit latrine), or ...
s, and 2,066 large external windows.
[Claridge, Amanda (1998). ''Rome: An Oxford Archaeological Guide'', First, Oxford, UK: Oxford University Press, 1998, pp. 59, 332–335. ]
The
Romans
Roman or Romans most often refers to:
*Rome, the capital city of Italy
* Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a lette ...
fortified their cities with massive, mortar-bound stone walls. The most famous of these are the largely extant
Aurelian Walls of
Rome
, established_title = Founded
, established_date = 753 BC
, founder = King Romulus (legendary)
, image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg
, map_caption ...
and the
Theodosian Walls
The Walls of Constantinople ( el, Τείχη της Κωνσταντινουπόλεως) are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul in Turkey) since its founding as the ...
of Constantinople, together with partial remains elsewhere. These are mostly city gates, like the Porta Nigra in Trier or Newport Arch in Lincoln, Lincolnshire, Lincoln. Hadrian's Wall was built by the Roman Empire across the width of what is now northern England following a visit by List of Roman Emperors, Roman Emperor Hadrian (AD 76–138) in AD 122.
India
![Dholavira gujarat](https://upload.wikimedia.org/wikipedia/commons/8/80/Dholavira_gujarat.jpg)
A number of forts dating from the Later Stone Age to the British Raj may be found in India. "Fort" is the word used in India for all old fortifications. Numerous Indus Valley civilisation, Indus Valley Civilization sites exhibit evidences of fortifications. While Dholavira has stone-built fortification walls, Harappa, 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. 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 Kosambi, Kaushambi, Mahasthangarh, Pataliputra, Mathura, Ahichchhatra, Rajgir, and Lauria Nandangarh. The earliest vedic brick fortification occurs in one of the stupa mounds of Lauria Nandangarh, which is 1.6 km in perimeter and oval in plan and encloses a habitation area. India currently has over 180 forts, with the state of Maharashtra alone having over 70 forts, which are also known as ''durg'',
many of them built by Shivaji, founder of the Maratha Empire, Maratha state. A large majority of forts in India are in North India. The most notable forts are the Red Fort at Delhi, the Agra Fort, Red Fort at Agra, the Chittor Fort and Mehrangarh Fort in Rajasthan, the Ranthambhor Fort, Amer Fort and Jaisalmer Fort also in Rajasthan and Gwalior Fort in Madhya Pradesh.
China
![20090529 Great Wall 8185](https://upload.wikimedia.org/wikipedia/commons/1/10/20090529_Great_Wall_8185.jpg)
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
A siege is a military blockade of a city, or fortress, with the intent of conquering by attrition, or a well-prepared assault. This derives from la, sedere, lit=to sit. Siege warfare is a form of constant, low-intensity conflict characteriz ...
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).
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 City Walls, Hangzhou, City Wall of Nanjing, Nanjing, the Old City (Shanghai), Old City of Shanghai, City Wall of Suzhou, Suzhou, Fortifications of Xi'an, 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.
Philippines
Spanish colonial fortifications
During the Spanish East Indies, Spanish Era several forts and outposts were built throughout the archipelago. Most notable is Intramuros, the old defensive walls, walled city of Manila located along the southern bank of the Pasig River. 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.
Partial listing of Spanish forts:
# Intramuros, Manila
# Cuartel de Santo Domingo, Santa Rosa, Laguna
# Cuyo Fort, Fuerza de Cuyo, Cuyo, Palawan
# Cagayancillo Fort, Fuerza de Cagayancillo, Cagayancillo, Palawan
# Fort Pilar, Real Fuerza de Nuestra Señora del Pilar de Zaragoza, Zamboanga City
# Fort San Felipe (Cavite), Fuerza de San Felipe, Cavite City
# Fort San Pedro, Fuerza de San Pedro, Cebu
# Fuerte dela Concepcion y del Triunfo, Ozamiz, Misamis Occidental
# Fort San Antonio Abad, Fuerza de San Antonio Abad, Manila
# Fort Pikit, Fuerza de Pikit, Pikit, Cotabato
# Romblon, Romblon, Fuerza de Santiago, Romblon, Romblon
# Jolo, Sulu, Fuerza de Jolo, Jolo, Sulu
# Masbate, Fuerza de Masbate, Masbate
# Bongabong, Oriental Mindoro, Fuerza de Bongabong, Bongabong, Oriental Mindoro
# Dapitan, Cotta de Dapitan, Dapitan, Zamboanga del Norte
# Tukuran, Zamboanga del Sur, Fuerte de Alfonso XII, Tukuran, Zamboanga del Sur
# Bacolod, Lanao del Norte, Fuerza de Bacolod, Bacolod, Lanao del Norte
# Guinsiliban, Camiguin, Guinsiliban Watchtower, Guinsiliban, Camiguin
# Laguindingan, Misamis Oriental, Laguindingan Watchtower, Laguindingan, Misamis Oriental
# Gumaca, Kutang San Diego, Gumaca, Quezon
# Luna, La Union, Baluarte Luna, Luna, La Union
Local fortifications
The Ivatan people of the northern islands of Batanes built their so-called ''idjang'' on hills and elevated areas 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.
![American flag raised over Fort Santiago 8-13-1898](https://upload.wikimedia.org/wikipedia/commons/e/ee/American_flag_raised_over_Fort_Santiago_8-13-1898.jpg)
The Igorot people, 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.
[Ancient and Pre-Spanish Era of the Philippines](_blank)
. Accessed September 04, 2008.
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 Sultanate of Maguindanao, 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 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. 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. Many of these forts were also destroyed by American expeditions, as a result, very very few kotas still stand to this day.
Notable Kotas:
* Kingdom of Maynila, Kota Selurong: an outpost of the Bruneian Empire in Luzon, later became the City of Manila.
* Cotabato City, 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"
* Jolo, Sulu, 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.
Pre-Islamic Arabia
During Muhammad's lifetime
![The Battle of the Trench](https://upload.wikimedia.org/wikipedia/commons/f/ff/The_Battle_of_the_Trench.jpg)
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 Prophets of Islam, Islamic prophet Muhammad, dug a trench, which together with Medina's natural fortifications, rendered the confederate cavalry (consisting of horses and Camel cavalry, 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 as a diplomat, 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.
[*]
During the Siege of Ta'if in January 630,
[ Note: Shawwal 8AH is January 630AD] Muhammad ordered his followers to attack enemies who fled from the Battle of Hunayn and sought refuge in the fortress of Taif.
Islamic world
Africa
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''.
The walls may have been constructed between the thirteenth and mid-fifteenth century CE
or, during the first millennium CE.
Strong citadels were also built other in areas of Africa. History of the Yoruba people, 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.
[July, pp. 11–39]
A military tactic of the Ashanti Empire, Ashanti was to create powerful log stockades at key points. This was employed in later wars against the British Empire, British to block British advances. Some of these fortifications were over a hundred yard 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.
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.
[Thornton, pp. 22–39]
Medieval Europe
Roman forts
In the Roman Republic and the Roman Empire, the Latin word ''castrum'', plural ''castra'', was a military-related term.
In Latin usage, the singular form ''castrum'' meant 'fort', while the plural form ''castra'' meant 'camp'. The singular and ...
and
hill fort
A hillfort is a type of earthwork used as a fortified refuge or defended settlement, located to exploit a rise in elevation for defensive advantage. They are typically European and of the Bronze Age or Iron Age. Some were used in the post-Roma ...
s were the main antecedents of castles in
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
, which emerged in the 9th century in the
Carolingian Empire
The Carolingian Empire (800–888) was a large Frankish-dominated empire in western and central Europe during the Early Middle Ages. It was ruled by the Carolingian dynasty, which had ruled as kings of the Franks since 751 and as kings of the ...
. The
Early Middle Ages
The Early Middle Ages (or early medieval period), sometimes controversially referred to as the Dark Ages, is typically regarded by historians as lasting from the late 5th or early 6th century to the 10th century. They marked the start of the Mi ...
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
A ditch is a small to moderate divot created to channel water. A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. Ditches ar ...
. From the 12th century hundreds of settlements of all sizes were founded all across Europe, which very often obtained the right of fortification soon afterwards.
![John Smith 1624 map of Bermuda with Forts 01](https://upload.wikimedia.org/wikipedia/commons/8/85/John_Smith_1624_map_of_Bermuda_with_Forts_01.jpg)
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 Ostsiedlung, 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 Republic of Venice, 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 Venetians the Ottoman architecture, Ottomans used to built smaller fortifications but in greater numbers, and only rarely fortified entire settlements such as Počitelj, Walled city of Vratnik, Vratnik and Walled city of Jajce, Jajce in Ottoman Bosnia, Bosnia.
Development after introduction of firearms
Medieval-style fortifications were largely made obsolete by the arrival of
cannon
A cannon is a large- caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder ...
s on the 14th century battlefield. Fortifications in the age of
black powder evolved into much lower structures with greater use of
ditches
A ditch is a small to moderate divot created to channel water. A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. Ditches ar ...
and earthworks (engineering), earth
ramparts 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 Fortification, Cyclopaedia, Volume 1](https://upload.wikimedia.org/wikipedia/commons/3/39/Table_of_Fortification%2C_Cyclopaedia%2C_Volume_1.jpg)
The evolution of this new style of fortification can be seen in transitional forts such as Sarzanello 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 are the fortifications of Rhodes which were ''frozen'' at 1522 so that Rhodes is the only European walled town that still shows the transition between the classical medieval fortification and the modern ones.
Fortifications also extended in depth, with protected batteries for defensive cannonry, to allow them to engage attacking cannon to keep them at a distance and prevent them bearing directly on the vulnerable walls.
![Suomenlinna](https://upload.wikimedia.org/wikipedia/commons/d/da/Suomenlinna.jpg)
The result was Star fort, star shaped fortifications with tier upon tier of hornworks and
bastions, of which Fort Bourtange is an excellent example. There are also extensive fortifications from this era in the Northern Europe, Nordic states and in Great Britain, Britain, the fortifications of Berwick-upon-Tweed and the harbour archipelago of Suomenlinna at Helsinki being fine examples.
19th century
The arrival of
explosive shell
A shell, in a military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military context. Modern usage ...
s 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 explosive 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.
![Malta Delimara one](https://upload.wikimedia.org/wikipedia/commons/6/6a/Malta_Delimara_one.jpg)
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 fort, 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.
![14-46-35-f-mutzig](https://upload.wikimedia.org/wikipedia/commons/4/42/14-46-35-f-mutzig.jpg)
Much of the fort moved underground. Deep passages and tunnels now connected the blockhouses and firing points in the ditch to the fort proper, with magazine (artillery), 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.
Gone were citadels surrounding towns: forts were to be moved to the outside of the cities some 12 km 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 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
Steel-and-
concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
fortifications were common during the 19th and early 20th centuries. However the advances in modern warfare since
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
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, for example Fort Campbell (Malta), Fort Campbell in Malta. 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 air power 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 produced 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.
![Image-GBU-24 Missile testmontage-gi BLU-109 bomb](https://upload.wikimedia.org/wikipedia/commons/6/68/Image-GBU-24_Missile_testmontage-gi_BLU-109_bomb.jpg)
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 antitank 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 into the strongest part of the Soviet Union, 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 cost.
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.
![NORADNorth-Portal](https://upload.wikimedia.org/wikipedia/commons/0/02/NORADNorth-Portal.jpg)
After World War II, intercontinental ballistic missiles capable of reaching much of the way around the world were developed, and 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 air 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 nuclear submarines capable of firing 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.
Aircraft can be protected by revetments, Hesco barriers, or hardened aircraft shelters which will protect from many types of attack. Larger aircraft types tend to be based outside the operational theatre.
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 tactics, 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 accident. 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 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/Camp Leatherneck, Leatherneck in
Afghanistan
Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...
. 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
![Fortaleza Ozama RD 11 2017 6495](https://upload.wikimedia.org/wikipedia/commons/3/39/Fortaleza_Ozama_RD_11_2017_6495.jpg)
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 conflict, 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 Company (military unit), companies. The reason for this is that static above ground forts can not 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, with supermaxes having some of the strongest of those. 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).
See also
* Border barrier
* Castra
* Citadel
* Coastal defence and fortification
* Defense line
* Defensive wall
* Hesco bastion
* Imperial fortress
* Kuruwa, walls of a Japanese castle
* List of fortifications
* List of forts
* Military camp
* Slighting
Fort components
* Abatis
* Banquette
* Barbed wire, razor wire, wire entanglement, and wire obstacle
* Bartizan
* Bastion
* Berm
* Capital (fortification), Capital
* Caponier
* Casemate
* Castle walls
* Czech hedgehog
* Defensive fighting position
* Ditch (fortification), Ditch
* Embrasure
* Glacis
* Gun turret
* Keep
* Lunette (fortification), Lunette
* Machicolation
* Outwork
* Palisade
* Parapet#Parapets in fortification, Parapet
* Pillbox (military), Pillbox
* Postern
* Ravelin
* Rampart (fortification), Rampart
* Revetment
* Sandbag
* Sangar (fortification), Sangar
* Counterscarp, Scarp and Counterscarp
* Turret (architecture), Turret
* ''Zwinger''
Types of forts and fortification
* Bastion fort (or star fort)
* Blockhouse
* Bunker
*
Castle
* Chinese city wall
* Compound (fortification), Compound
* Defensive wall
* Diaolou
* Fire support base
* Flak tower
* Fortress church or fortified church
* Gord (archaeology), Grad, a Slavic wooden fortified settlement
* Gusuku, fortifications in the Ryukyu Islands
* Korean fortress
* Hill fort
* Land battery
* Martello tower
* Medieval fortification
* Missile launch facility
* Pā, a 19th-century Māori fortification
* Peel tower
* Polygonal fort
* Promontory fort
* Redoubt
* Stockade
Fortification and siege warfare
* Medieval warfare
* Military engineering
* Military history
* Siege
* Siege engine
Notable experts
* Henri Alexis Brialmont
* César Cui
* Bernard de Gomme
* Francesco Laparelli
* Mozi
* Diades of Pella
* James of Saint George
* Fritz Todt
* Menno van Coehoorn
* Sébastien Le Prestre de Vauban
* Maximilian von Welsch
Notes
References
*
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: 200
copy* Thornton, John Kelly ''Warfare in Atlantic Africa'', 1500–1800, Routledge: 1999
External links
Fortress Study Group*
ICOFORT
{{Authority control
Fortifications,
Military strategy
Military installations
Forts