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124-543: Existing ancient walls are almost always masonry structures, although brick and timber-built variants are also known. Depending on the topography of the area surrounding the city or the settlement the wall is intended to protect, elements of the terrain such as rivers or coastlines may be incorporated in order to make the wall more effective. Walls may only be crossed by entering the appropriate city gate and are often supplemented with towers. The practice of building these massive walls, though having its origins in prehistory,

248-544: A Qing incursion in 1638. By 1641, there were ten bastion forts in the county. Before bastion forts could spread any further, the Ming dynasty fell in 1644, and they were largely forgotten as the Qing dynasty was on the offensive most of the time and had no use for them. In the wake of city growth and the ensuing change of defensive strategy, focusing more on the defense of forts around cities, many city walls were demolished. Also,

372-407: A CMU wall having much greater lateral and tensile strength than unreinforced walls. "Architectural masonry is the evolvement of standard concrete masonry blocks into aesthetically pleasing concrete masonry units (CMUs)". CMUs can be manufactured to provide a variety of surface appearances. They can be colored during manufacturing or stained or painted after installation. They can be split as part of

496-507: A bit more than a third the width of a major wall in China. According to Philo the width of a wall had to be 4.5 metres (15 ft) thick to be able to withstand ancient (non-gunpowder) siege engines. European walls of the 1200s and 1300s could reach the Roman equivalents but rarely exceeded them in length, width, and height, remaining around 2 metres (6 ft 7 in) thick. When referring to

620-588: A city fully enclosed by walls was not fully developed in Southeast Asia until the arrival of Europeans. However, Burma serves an exception, as they had a longer tradition of fortified walled towns; towns in Burma had city walls by 1566. Besides that, Rangoon in 1755 had stockades made of teak logs on a ground rampart . The city was fortified with six city gates with each gate flanked by massive brick towers. In other areas of Southeast Asia, city walls spread in

744-404: A city or fortress that cannot be easily taken by a quick assault, and which refuses to surrender . Sieges involve surrounding the target to block provision of supplies and reinforcement or escape of troops (a tactic known as " investment "). This is typically coupled with attempts to reduce the fortifications by means of siege engines , artillery bombardment, mining (also known as sapping), or

868-463: A city, or fortress , with the intent of conquering by attrition, or by well-prepared assault. Siege warfare (also called siegecraft or poliorcetics ) 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 siege occurs when an attacker encounters

992-489: A cost benefit hypothesis, where the Ming recognized the highly resistant nature of their walls to structural damage, and could not imagine any affordable development of the guns available to them at the time to be capable of breaching said walls. Even as late as the 1490s a Florentine diplomat considered the French claim that "their artillery is capable of creating a breach in a wall of eight feet in thickness" to be ridiculous and

1116-427: A darker color or an irregular shape. Others may use antique salvage bricks, or new bricks may be artificially aged by applying various surface treatments, such as tumbling. The attempts at rusticity of the late 20th century have been carried forward by masons specializing in a free, artistic style, where the courses are intentionally not straight, instead weaving to form more organic impressions. A crinkle-crankle wall

1240-575: A masonry wall is not entirely dependent on the bond between the building material and the mortar; the friction between the interlocking blocks of masonry is often strong enough to provide a great deal of strength on its own. The blocks sometimes have grooves or other surface features added to enhance this interlocking, and some dry set masonry structures forgo mortar altogether. Stone blocks used in masonry can be dressed or rough, though in both examples corners, door and window jambs, and similar areas are usually dressed. Stonemasonry utilizing dressed stones

1364-742: A maximum thickness of 43 metres and an average thickness of 20–30 metres. Ming prefectural and provincial capital walls were 10 to 20 metres (33 to 66 ft) thick at the base and 5 to 10 metres (16 to 33 ft) at the top. In Europe the height of wall construction was reached under the Roman Empire , whose walls often reached 10 metres (33 ft) in height, the same as many Chinese city walls, but were only 1.5 to 2.5 metres (4 ft 11 in to 8 ft 2 in) thick. Rome's Servian Walls reached 3.6 and 4 metres (12 and 13 ft) in thickness and 6 to 10 metres (20 to 33 ft) in height. Other fortifications also reached these specifications across

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1488-419: A minor force could seldom be maintained. A besieging army, encamped in possibly squalid field conditions and dependent on the countryside and its own supply lines for food, could very well be threatened with the disease and starvation intended for the besieged. To end a siege more rapidly, various methods were developed in ancient and medieval times to counter fortifications, and a large variety of siege engines

1612-508: A non-staggered bond. The wide selection of brick styles and types generally available in industrialized nations allow much variety in the appearance of the final product. In buildings built during the 1950s-1970s, a high degree of uniformity of brick and accuracy in masonry was typical. In the period since then this style was thought to be too sterile, so attempts were made to emulate older, rougher work. Some brick surfaces are made to look particularly rustic by including burnt bricks, which have

1736-408: A permanent colored facing (typically composed of polyester resins, silica sand and various other chemicals) to a concrete masonry unit, providing a smooth impervious surface." Glass block or glass brick are blocks made from glass and provide a translucent to clear vision through the block. A masonry veneer wall consists of masonry units, usually clay-based bricks, installed on one or both sides of

1860-423: A purely military and defensive purpose, towers also played a representative and artistic role in the conception of a fortified complex. The architecture of the city thus competed with that of the castle of the noblemen and city walls were often a manifestation of the pride of a particular city. Urban areas outside the city walls, so-called Vorstädte , were often enclosed by their own set of walls and integrated into

1984-405: A rebellious Anatolian vassal in the 14th century BC ended when the queen mother came out of the city and begged for mercy on behalf of her people. The Hittite campaign against the kingdom of Mitanni in the 14th century BC bypassed the fortified city of Carchemish . If the main objective of a campaign was not the conquest of a particular city, it could simply be passed by. When the main objective of

2108-421: A response to gunpowder artillery, European fortifications began displaying architectural principles such as lower and thicker walls in the mid-1400s. Cannon towers were built with artillery rooms where cannons could discharge fire from slits in the walls. However, this proved problematic as the slow rate of fire, reverberating concussions, and noxious fumes produced greatly hindered defenders. Gun towers also limited

2232-403: A siege might be a surprise attack, attempting to overwhelm the defenders before they were ready or were even aware there was a threat. This was how William de Forz captured Fotheringhay Castle in 1221. The most common practice of siege warfare was to lay siege and just wait for the surrender of the enemies inside or, quite commonly, to coerce someone inside to betray the fortification. During

2356-436: A siege progressed, the surrounding army would build earthworks (a line of circumvallation ) to completely encircle their target, preventing food, water, and other supplies from reaching the besieged city. If sufficiently desperate as the siege progressed, defenders and civilians might have been reduced to eating anything vaguely edible – horses, family pets, the leather from shoes, and even each other . The Hittite siege of

2480-631: A simple battering ram had come into use in the previous millennium, the Assyrians improved siege warfare and used huge wooden tower-shaped battering rams with archers positioned on top. In ancient China, sieges of city walls (along with naval battles) were portrayed on bronze 'hu' vessels , like those found in Chengdu , Sichuan in 1965, which have been dated to the Warring States period (5th to 3rd centuries BC). An attacker's first act in

2604-556: A single "embassy district", enclosed by a fortified complex with walls and towers – this usually occurs in regions where the embassies run a high risk of being target of attacks. An early example of such a compound was the Legation Quarter in Beijing in the late 19th and early 20th centuries. Most of these modern city walls are made of steel and concrete. Vertical concrete plates are put together so as to allow

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2728-431: A structurally independent wall usually constructed of wood or masonry. In this context, the brick masonry is primarily decorative, not structural. The brick veneer is generally connected to the structural wall by brick ties (metal strips that are attached to the structural wall, as well as the mortar joints of the brick veneer). There is typically an air gap between the brick veneer and the structural wall. As clay-based brick

2852-475: A very thick wall in medieval Europe, what is usually meant is a wall of 2.5 metres (8 ft 2 in) in width, which would have been considered thin in a Chinese context. There are some exceptions such as the Hillfort of Otzenhausen , a Celtic ringfort with a thickness of 40 metres (130 ft) in some parts, but Celtic fort-building practices died out in the early medieval period. Andrade goes on to note that

2976-478: A wall of a given size. Furthermore, cinder and concrete blocks typically have much lower water absorption rates than brick. They often are used as the structural core for veneered brick masonry or are used alone for the walls of factories, garages, and other industrial-style buildings where such appearance is acceptable or desirable. Such blocks often receive a stucco surface for decoration. Surface-bonding cement , which contains synthetic fibers for reinforcement,

3100-460: A wheeled siege ramp with grappling hooks known as the Cloud Bridge (the protractible, folded ramp slinging forward by means of a counterweight with rope and pulley), and wheeled 'hook-carts' used to latch large iron hooks onto the tops of walls to pull them down. When enemies attempted to dig tunnels under walls for mining or entry into the city, the defenders used large bellows (the type

3224-558: Is a brick wall that follows a serpentine path, rather than a straight line. This type of wall is more resistant to toppling than a straight wall; so much so that it may be made of a single wythe of unreinforced brick and so despite its longer length may be more economical than a straight wall. Blocks of cinder concrete ( cinder blocks or breezeblocks ), ordinary concrete ( concrete blocks ), or hollow tile are generically known as Concrete Masonry Units (CMUs). They usually are much larger than ordinary bricks and so are much faster to lay for

3348-420: Is generally a highly durable form of construction. However, the materials used, the quality of the mortar and workmanship, and the pattern in which the units are assembled can substantially affect the durability of the overall masonry construction. A person who constructs masonry is called a mason or bricklayer . These are both classified as construction trades . Masonry is one of the oldest building crafts in

3472-456: Is known as ashlar masonry, whereas masonry using irregularly shaped stones is known as rubble masonry . Both rubble and ashlar masonry can be laid in coursed rows of even height through the careful selection or cutting of stones, but a great deal of stone masonry is uncoursed. Solid brickwork is made of two or more wythes of bricks with the units running horizontally (called stretcher bricks) bound together with bricks running transverse to

3596-421: Is known from Egyptian tomb reliefs of the 24th century BC, showing Egyptian soldiers storming Canaanite town walls on wheeled siege ladders. Later Egyptian temple reliefs of the 13th century BC portray the violent Siege of Dapur , a Syrian city, with soldiers climbing scale ladders supported by archers. Assyrian palace reliefs of the 9th to 7th centuries BC display sieges of several Near Eastern cities. Though

3720-509: Is one of the world's oldest known walled cities. Before that, the proto-city of Jericho in the West Bank had a wall surrounding it as early as the 8th millennium   BC. The earliest known town wall in Europe is of Solnitsata , built in the 6th or 5th millennium BC. The Assyrians deployed large labour forces to build new palaces, temples and defensive walls. Babylon was one of

3844-549: Is only as long as the wire they are composed of and if used in severe climates (such as shore-side in a salt water environment) must be made of appropriate corrosion-resistant wire. Most modern gabions are rectangular. Earlier gabions were often cylindrical wicker baskets, open at both ends, used usually for temporary, often military, construction. Similar work can be done with finer aggregates using cellular confinement . Masonry walls have an endothermic effect of its hydrates , as in chemically bound water , unbound moisture from

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3968-717: Is sometimes used in this application and can impart extra strength to a block wall. Surface-bonding cement is often pre-colored and can be stained or painted thus resulting in a finished stucco-like surface. The primary structural advantage of concrete blocks in comparison to smaller clay-based bricks is that a CMU wall can be reinforced by filling the block voids with concrete with or without steel rebar . Generally, certain voids are designated for filling and reinforcement, particularly at corners, wall-ends, and openings while other voids are left empty. This increases wall strength and stability more economically than filling and reinforcing all voids. Typically, structures made of CMUs will have

4092-754: Is the Romanian Bran Castle , which was intended to protect nearby Kronstadt (today's Braşov ). The city walls were often connected to the fortifications of hill castles via additional walls. Thus the defenses were made up of city and castle fortifications taken together. Several examples of this are preserved, for example in Germany Hirschhorn on the Neckar, Königsberg and Pappenheim , Franken, Burghausen in Oberbayern and many more. A few castles were more directly incorporated into

4216-466: Is the craft of building a structure with brick, stone, or similar material, including mortar plastering which are often laid in, bound, and pasted together by mortar . The term masonry can also refer to the building units (stone, brick, etc.) themselves. The common materials of masonry construction are bricks and building stone , rocks such as marble , granite , and limestone , cast stone , concrete blocks , glass blocks , and adobe . Masonry

4340-407: Is to build a line of earth-works, consisting of a rampart and trench, surrounding it. During the process of circumvallation, the attacking force can be set upon by another force, an ally of the besieged place, due to the lengthy amount of time required to force it to capitulate. A defensive ring of forts outside the ring of circumvallated forts, called contravallation, is also sometimes used to defend

4464-496: Is usually not completely waterproof, the structural wall will often have a water-resistant surface (usually tar paper ) and weep holes can be left at the base of the brick veneer to drain moisture that accumulates inside the air gap. Concrete blocks, real and cultured stones , and veneer adobe are sometimes used in a very similar veneer fashion. Most insulated buildings that use concrete block, brick, adobe, stone, veneers or some combination thereof feature interior insulation in

4588-464: The Huo Long Jing , this manuscript of Jiao Yu recorded an earlier Song-era cast-iron cannon known as the 'flying-cloud thunderclap eruptor' (fei yun pi-li pao). The manuscript stated that ( Wade–Giles spelling): The shells ( phao ) are made of cast iron, as large as a bowl and shaped like a ball. Inside they contain half a pound of 'magic' gunpowder ( shen huo ). They are sent flying towards

4712-719: The Battle of Alesia , the Roman legions created two huge fortified walls around the city. The inner circumvallation, 16 km (10 mi), held in Vercingetorix 's forces, while the outer contravallation kept relief from reaching them. The Romans held the ground in between the two walls. The besieged Gauls, facing starvation, eventually surrendered after their relief force met defeat against Caesar's auxiliary cavalry. The Sicarii Zealots who defended Masada in AD 73 were defeated by

4836-510: 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 neighboring communities quarreled constantly about the control of prime agricultural land. Mundigak ( c.  2500   BC ) in present-day south-east Afghanistan has defensive walls and square bastions of sun dried bricks. The concept of

4960-730: The Indus Valley civilization were also fortified. By about 3500 BC, hundreds of small farming villages dotted the Indus River 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 dikes and defensive walls, for neighbouring communities quarrelled constantly about the control of prime agricultural land. Mundigak (c. 2500 BC) in present-day south-east Afghanistan has defensive walls and square bastions of sun-dried bricks . City walls and fortifications were essential for

5084-707: The Piankhi stela , records how the Nubians laid siege to and conquered several Egyptian cities by using battering rams, archers, and slingers and building causeways across moats. During the Peloponnesian War , one hundred sieges were attempted and fifty-eight ended with the surrender of the besieged area. Alexander the Great 's army successfully besieged many powerful cities during his conquests. Two of his most impressive achievements in siegecraft took place in

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5208-530: The Siege of Tyre and the Siege of the Sogdian Rock . His engineers built a causeway that was originally 60 m (200 ft) wide and reached the range of his torsion-powered artillery, while his soldiers pushed siege towers housing stone throwers and light catapults to bombard the city walls. Most conquerors before him had found Tyre , a Phoenician island-city about 1 km (1,100 yd) from

5332-615: The State of Zhao , Handan , founded in 386 BC, also had walls that were 20 m (66 ft) wide at the base; they were 15 m (49 ft) tall, with two separate sides of its rectangular enclosure at a length of 1,400 m (1,530 yd). The cities of the Indus Valley Civilization showed less effort in constructing defences, as did the Minoan civilization on Crete . These civilizations probably relied more on

5456-759: The Tang dynasty (618–907   AD). Sections of the Great Wall had been built prior to the Qin dynasty (221–207   BC) and subsequently connected and fortified during the Qin dynasty, although its present form was mostly an engineering feat and remodeling of the Ming dynasty (1368–1644   AD). The large walls of Pingyao serve as one example. Likewise, the walls of the Forbidden City in Beijing were established in

5580-526: The Vietnam War . Until the invention of gunpowder -based weapons (and the resulting higher-velocity projectiles), the balance of power and logistics definitely favored the defender. With the invention of gunpowder, cannon and mortars and howitzers (in modern times), the traditional methods of defense became less effective against a determined siege. Although there are numerous ancient accounts of cities being sacked, few contain any clues to how this

5704-546: The Yuan dynasty in 1271, was very effective, allowing the Mongols to sweep through large areas. Even if they could not enter some of the more well-fortified cities, they used innovative battle tactics to grab hold of the land and the people: By concentrating on the field armies, the strongholds had to wait. Of course, smaller fortresses, or ones easily surprised, were taken as they came along. This had two effects. First, it cut off

5828-681: The concentric castle from the period of the Crusades —and more dangerous to attackers—witness the increasing use of machicolations and murder-holes , as well the preparation of hot or incendiary substances . Arrowslits (also called arrow loops or loopholes), sally ports (airlock-like doors) for sallies and deep water wells were also integral means of resisting siege at this time. Particular attention would be paid to defending entrances, with gates protected by drawbridges , portcullises , and barbicans . Moats and other water defenses, whether natural or augmented, were also vital to defenders. In

5952-476: The early modern period , siege warfare dominated the conduct of war in Europe. Leonardo da Vinci gained some of his renown from design of fortifications. Medieval campaigns were generally designed around a succession of sieges. In the Napoleonic era , increasing use of ever more powerful cannons reduced the value of fortifications. In the 20th century, the significance of the classical siege declined. With

6076-446: The 16th and 17th century along with the rapid growth of cities in this period as a need to defend against European naval attack. Ayutthaya built its walls in 1550 and Banten , Jepara , Tuban and Surabaya all had theirs by 1600; while Makassar had theirs by 1634. A sea wall was the main defense for Gelgel . For cities that did not have city walls, the least it would have had was a stockaded citadel . This wooden walled area housed

6200-680: The 16th century. The bastion and star fort was developed in Italy, where the Florentine engineer Giuliano da Sangallo (1445–1516) compiled a comprehensive defensive plan using the geometric bastion and full trace italienne that became widespread in Europe. The main distinguishing features of the star fort were its angle bastions, each placed to support their neighbor with lethal crossfire, covering all angles, making them extremely difficult to engage with and attack. Angle bastions consisted of two faces and two flanks. Artillery positions positioned at

6324-495: The 19th century, less emphasis was placed on preserving the fortifications for the sake of their architectural or historical value – on the one hand, complete fortifications were restored ( Carcassonne ), on the other hand many structures were demolished in an effort to modernize the cities. One exception to this is the "monument preservation" law by the Bavarian King Ludwig I of Bavaria , which led to

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6448-455: The Chinese commonly used in heating up a blast furnace for smelting cast iron ) to pump smoke into the tunnels in order to suffocate the intruders. Advances in the prosecution of sieges in ancient and medieval times naturally encouraged the development of a variety of defensive countermeasures. In particular, medieval fortifications became progressively stronger—for example, the advent of

6572-755: The European Middle Ages , virtually all large cities had city walls— Dubrovnik in Dalmatia is a well-preserved example—and more important cities had citadels , forts , or castles . Great effort was expended to ensure a good water supply inside the city in case of siege. In some cases, long tunnels were constructed to carry water into the city. Complex systems of tunnels were used for storage and communications in medieval cities like Tábor in Bohemia , similar to those used much later in Vietnam during

6696-512: The French "braggarts by nature". Very rarely did cannons blast breaches in city walls in Chinese warfare. This may have been partly due to cultural tradition. Famous military commanders such as Sun Tzu and Zheng Zhilong recommended not to directly attack cities and storm their walls. Even when direct assaults were made with cannons, it was usually by focusing on the gates rather than the walls. There were instances where cannons were used against walled fortifications, such as by Koxinga , but only in

6820-650: The Roman legions, who built a ramp 100 metres (330 ft) high up to the fortress's west wall. During the Roman–Persian Wars , siege warfare was extensively being used by both sides. In the Middle Ages, the Mongol Empire 's campaign against China (then comprising the Western Xia dynasty , Jin dynasty , and Southern Song dynasty ) by Genghis Khan until Kublai Khan , who eventually established

6944-782: The Southern Song Chinese held out against the enormous barrage of Mongol attacks. Much of this success in defense lay in the world's first use of gunpowder (i.e. with early flamethrowers , grenades , firearms , cannons, and land mines ) to fight back against the Khitans , the Tanguts , the Jurchens , and then the Mongols. The Chinese of the Song period also discovered the explosive potential of packing hollowed cannonball shells with gunpowder. Written later c.  1350 in

7068-556: The advent of mobile warfare , a single fortified stronghold is no longer as decisive as it once was. While traditional sieges do still occur, they are not as common as they once were due to changes in modes of battle, principally the ease by which huge volumes of destructive power can be directed onto a static target. Modern sieges are more commonly the result of smaller hostage, militant, or extreme resisting arrest situations. The Assyrians deployed large labour forces to build new palaces, temples, and defensive walls. Some settlements in

7192-496: The ancient Near East in historical sources and in art, there are very few examples of siege systems that have been found archaeologically. Of the few examples, several are noteworthy: The earliest representations of siege warfare have been dated to the Protodynastic Period of Egypt , c.  3000 BC . These show the symbolic destruction of city walls by divine animals using hoes. The first siege equipment

7316-745: The ancient site of Mycenae (famous for the huge stone blocks of its ' cyclopean ' walls). In classical era Greece, the city of Athens built a long set of parallel stone walls called the Long Walls that reached their guarded seaport at Piraeus . Exceptions were few, but neither ancient Sparta nor ancient Rome had walls for a long time, choosing to rely on their militaries for defense 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 . The Romans later fortified their cities with massive, mortar-bound stone walls. Among these are

7440-531: The attackers from outside. Ancient cities in the Middle East show archaeological evidence of fortified city walls . During the Warring States period of ancient China , there is both textual and archaeological evidence of prolonged sieges and siege machinery used against the defenders of city walls . Siege machinery was also a tradition of the ancient Greco-Roman world . During the Renaissance and

7564-676: The booty of his conquest undamaged, and retain his men and equipment intact, for the price of a well-placed bribe to a disgruntled gatekeeper. The Assyrian siege of Jerusalem in the 8th century BC came to an end when the Israelites bought them off with gifts and tribute, according to the Assyrian account, or when the Assyrian camp was struck by mass death, according to the Biblical account. Due to logistics, long-lasting sieges involving

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7688-473: The campaign had been fulfilled, the Hittite army returned to Carchemish and the city fell after an eight-day siege. Disease was another effective siege weapon, although the attackers were often as vulnerable as the defenders. In some instances, catapults or similar weapons were used to fling diseased animals over city walls in an early example of biological warfare . If all else failed, a besieger could claim

7812-543: The case of small villages. During Koxinga's career, there is only one recorded case of capturing a settlement by bombarding its walls: the siege of Taizhou in 1658. In 1662, the Dutch found that bombarding the walls of a town in Fujian Province had no effect and they focused on the gates instead just as in Chinese warfare. In 1841, a 74-gun British warship bombarded a Chinese coastal fort near Guangzhou and found that it

7936-416: The circumvention of the city, through which many important trade routes passed, thus ensuring that tolls were paid when the caravans passed through the city gates, and that the local market was visited by the trade caravans. Furthermore, additional signaling and observation towers were frequently built outside the city, and were sometimes fortified in a castle-like fashion. The border of the area of influence of

8060-475: The city was often partially or fully defended by elaborate ditches, walls and hedges. The crossing points were usually guarded by gates or gate houses. These defenses were regularly checked by riders, who often also served as the gate keepers. Long stretches of these defenses can still be seen to this day, and even some gates are still intact. To further protect their territory, rich cities also established castles in their area of influence. An example of this practice

8184-534: The concrete block, and the poured concrete if the hollow cores inside the blocks are filled. Masonry can withstand temperatures up to 1,000 °F (538 °C) and it can withstand direct exposure to fire for up to 4 hours. In addition to that, concrete masonry keeps fires contained to their room of origin 93% of the time. For those reasons, concrete and masonry units hold the highest flame spread index classification, Class A. Fire cuts can be used to increase safety and reduce fire damage to masonry buildings. From

8308-535: The construction of the "European Rampart" alongside its border with Russia to be able to successfully apply for a visa-free movement with the European Union. At its simplest, a defensive wall consists of a wall enclosure and its gates. For the most part, the top of the walls were accessible, with the outside of the walls having tall parapets with embrasures or merlons . North of the Alps, this passageway at

8432-648: The cores remain unfilled. Filling some or all of the cores with concrete or concrete with steel reinforcement (typically rebar ) offers much greater tensile and lateral strength to structures. One problem with masonry walls is that they rely mainly on their weight to keep them in place; each block or brick is only loosely connected to the next via a thin layer of mortar. This is why they do not perform well in earthquakes, when entire buildings are shaken horizontally. Many collapses during earthquakes occur in buildings that have load-bearing masonry walls. Besides, heavier buildings having masonry suffer more damage. The strength of

8556-525: The defence of the first cities in the ancient Near East . The walls were built of mudbricks, stone, wood, or a combination of these materials, depending on local availability. They may also have served the dual purpose of showing potential enemies the might of the kingdom. The great walls surrounding the Sumerian city of Uruk gained a widespread reputation. The walls were 9.5 km (5.9 mi) in length, and up to 12 m (39 ft) in height. Later,

8680-466: The defence of their outer borders or sea shores. Unlike the ancient Minoan civilization, the Mycenaean Greeks emphasized the need for fortifications alongside natural defences of mountainous terrain, such as the massive Cyclopean walls built at Mycenae and other adjacent Late Bronze Age (c. 1600–1100 BC) centers of central and southern Greece. Although there are depictions of sieges from

8804-538: The defense of the city. These areas were often inhabited by the poorer population and held the "noxious trades". In many cities, a new wall was built once the city had grown outside of the old wall. This can often still be seen in the layout of the city, for example in Nördlingen , and sometimes even a few of the old gate towers are preserved, such as the white tower in Nuremberg . Additional constructions prevented

8928-427: The defensive strategy of the city (e.g. Nuremberg , Zons , Carcassonne ), or the cities were directly outside the castle as a sort of "pre-castle" (Coucy-le-Chateau, Conwy and others). Larger cities often had multiple stewards – for example Augsburg was divided into a Reichstadt and a clerical city. These different parts were often separated by their own fortifications. Masonry Masonry

9052-613: The demands on stored food and water. During the Warring States period in China (481–221 BC), warfare lost its honorable, gentlemen's duty that was found in the previous era of the Spring and Autumn period , and became more practical, competitive, cut-throat, and efficient for gaining victory. The Chinese invention of the hand-held, trigger-mechanism crossbow during this period revolutionized warfare, giving greater emphasis to infantry and cavalry and less to traditional chariot warfare. The philosophically pacifist Mohists (followers of

9176-417: The early Middle Ages also 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 AD hundreds of settlements of all sizes were founded all across Europe, which very often obtained the right of fortification soon afterwards. Several medieval town walls have survived into

9300-463: The early 15th century by the Yongle Emperor . According to Tonio Andrade , the immense thickness of Chinese city walls prevented larger cannons from being developed, since even industrial era artillery had trouble breaching Chinese walls. Eupseongs (Hangul: 읍성), 'city fortresses', which served both military and administrative functions, have been constructed since the time of Silla until

9424-453: The empire, but all these paled in comparison to contemporary Chinese walls, which could reach a thickness of 20 metres (66 ft) at the base in extreme cases. Even the walls of Constantinople which have been described as "the most famous and complicated system of defence in the civilized world," could not match up to a major Chinese city wall. Had both the outer and inner walls of Constantinople been combined they would have only reached roughly

9548-592: The end of the Joseon dynasty . Throughout the period of the Joseon dynasty eupseongs were modified and renovated, and new eupseongs were built, but in 1910 Japan (the occupying power of Korea) issued an order for their demolition, resulting in most being destroyed. Studies of the ruins and reconstructions of the ancient city walls are currently being undertaken at some sites. In ancient Greece , large stone walls had been built in Mycenaean Greece , such as

9672-408: The enemy camp from an eruptor ( mu phao ); and when they get there a sound like a thunder-clap is heard, and flashes of light appear. If ten of these shells are fired successfully into the enemy camp, the whole place will be set ablaze... During the Ming dynasty (AD 1368–1644), the Chinese were very concerned with city planning in regards to gunpowder warfare. The site for constructing the walls and

9796-573: The energy of artillery shots. Walls were constructed using wooden frameworks which were filled with layers of earth tamped down to a highly compact state, and once that was completed the frameworks were removed for use in the next wall section. Starting from the Song dynasty these walls were improved with an outer layer of bricks or stone to prevent erosion, and during the Ming, earthworks were interspersed with stone and rubble. Most Chinese walls were also sloped rather than vertical to better deflect projectile energy. The defensive response to cannon in Europe

9920-554: The field, he was unable to capture Rome itself. The legionary armies of the Roman Republic and Empire are noted as being particularly skilled and determined in siege warfare. An astonishing number and variety of sieges, for example, formed the core of Julius Caesar 's mid-1st-century BC conquest of Gaul (modern France). In his Commentarii de Bello Gallico ( Commentaries on the Gallic War ), Caesar describes how, at

10044-494: The first night while laying siege to a city, the leader of the Mongol forces would lead from a white tent : if the city surrendered, all would be spared. On the second day, he would use a red tent: if the city surrendered, the men would all be killed, but the rest would be spared. On the third day, he would use a black tent: no quarter would be given. However, the Chinese were not completely defenseless, and from AD 1234 until 1279,

10168-403: The flanks could fire parallel into the opposite bastion's line of fire, thus providing two lines of cover fire against an armed assault on the wall, and preventing mining parties from finding refuge. Meanwhile, artillery positioned on the bastion platform could fire frontally from the two faces, also providing overlapping fire with the opposite bastion. Overlapping mutually supporting defensive fire

10292-411: The form of fiberglass batts between wooden wall studs or in the form of rigid insulation boards covered with plaster or drywall . In most climates this insulation is much more effective on the exterior of the wall, allowing the building interior to take advantage of the aforementioned thermal mass of the masonry. This technique does, however, require some sort of weather-resistant exterior surface over

10416-403: The fortification's walls, could allow the attackers to fire down upon the defenders and also advance troops to the wall with less danger than using ladders. In addition to launching projectiles at the fortifications or defenders, it was also quite common to attempt to undermine the fortifications, causing them to collapse. This could be accomplished by digging a tunnel beneath the foundations of

10540-443: The improbably high numbers which he used for both the Mongols and the defenders do give one a sense of the large numbers of machines used at a single siege. Another Mongol tactic was to use catapults to launch corpses of plague victims into besieged cities. The disease-carrying fleas from the bodies would then infest the city, and the plague would spread, allowing the city to be easily captured, although this transmission mechanism

10664-464: The insulation and, consequently, is generally more expensive. Gabions are baskets, usually now of zinc -protected steel ( galvanized steel ) that are filled with fractured stone of medium size. These will act as a single unit and are stacked with setbacks to form a revetment or retaining wall . They have the advantage of being well drained, flexible, and resistant to flood, water flow from above, frost damage, and soil flow. Their expected useful life

10788-436: The invention of gunpowder rendered walls less effective, as siege cannons could then be used to blast through walls, allowing armies to simply march through. Today, the presence of former city fortifications can often only be deduced from the presence of ditches, ring roads or parks. Furthermore, some street names hint at the presence of fortifications in times past, for example when words such as "wall" or "glacis" occur. In

10912-884: The largely extant Aurelian Walls of Rome and the Theodosian Walls of Constantinople , together with partial remains elsewhere. These are mostly city gates, like the Porta Nigra in Trier or Newport Arch in Lincoln . In Central Europe, the Celts built large fortified settlements which the Romans called oppida , whose walls seem partially influenced by those built in the Mediterranean. The fortifications were continuously expanded and improved. Apart from these,

11036-461: The least space in between them, and are rooted firmly in the ground. The top of the wall is often protruding and beset with barbed wire in order to make climbing them more difficult. These walls are usually built in straight lines and covered by watchtowers at the corners. Double walls with an interstitial "zone of fire", as the former Berlin Wall had, are now rare. In September 2014, Ukraine announced

11160-540: The mainland, impregnable. The Macedonians built a mole , a raised spit of earth across the water, by piling stones up on a natural land bridge that extended underwater to the island, and although the Tyrians rallied by sending a fire ship to destroy the towers, and captured the mole in a swarming frenzy, the city eventually fell to the Macedonians after a seven-month siege. In complete contrast to Tyre, Sogdian Rock

11284-457: The manufacturing process, giving the blocks a rough face replicating the appearance of natural stone, such as brownstone . CMUs may also be scored, ribbed, sandblasted, polished, striated (raked or brushed), include decorative aggregates, be allowed to slump in a controlled fashion during curing, or include several of these techniques in their manufacture to provide a decorative appearance. "Glazed concrete masonry units are manufactured by bonding

11408-472: The medieval period, negotiations would frequently take place during the early part of the siege. An attacker – aware of a prolonged siege's great cost in time, money, and lives – might offer generous terms to a defender who surrendered quickly. The defending troops would be allowed to march away unharmed, often retaining their weapons. However, a garrison commander who was thought to have surrendered too quickly might face execution by his own side for treason. As

11532-607: The modern age, such as the walled towns of Austria , walls of Tallinn , or the town walls of York and Canterbury in England, as well as Nordlingen , Dinkelsbühl and Rothenburg ob der Tauber in Germany. In Spain, Avila and Tossa del Mar hosts surviving medieval walls while Lugo has an intact Roman wall. The founding of urban centers was an important means of territorial expansion and many cities, especially in central and eastern Europe, were founded for this purpose during

11656-683: 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 Persians built defensive walls to protect their territories, notably the Derbent Wall and the Great Wall of Gorgan built on the either sides of the Caspian Sea against nomadic nations. Some settlements in the Indus Valley civilization were also fortified. By about 3500   BC, hundreds of small farming villages dotted

11780-506: The natives experienced great difficulty in uprooting European invaders. In China, Sun Yuanhua advocated for the construction of angled bastion forts in his Xifashenji so that their cannons could better support each other. The officials Han Yun and Han Lin noted that cannons on square forts could not support each side as well as bastion forts. Their efforts to construct bastion forts, and their results, were limited. Ma Weicheng built two bastion forts in his home county, which helped fend off

11904-669: The nearly complete preservation of many monuments such as the Rothenburg ob der Tauber , Nördlingen and Dinkelsbühl . The countless small fortified towns in the Franconia region were also preserved as a consequence of this edict. Walls and fortified wall structures were still built in the modern era. They did not, however, have the original purpose of being a structure able to resist a prolonged siege or bombardment. Modern examples of defensive walls include: Additionally, in some countries, different embassies may be grouped together in

12028-400: The period of Eastern settlement . 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. While gunpowder and cannons were invented in China, China never developed wall breaking artillery to the same extent as other parts of the world. Part of

12152-417: The philosopher Mozi ) of the 5th century BC believed in aiding the defensive warfare of smaller Chinese states against the hostile offensive warfare of larger domineering states. The Mohists were renowned in the smaller states (and the enemies of the larger states) for the inventions of siege machinery to scale or destroy walls. These included traction trebuchet catapults , 8-foot (2.4 m) high ballistas ,

12276-419: The point of view of material modeling, masonry is a special material of extreme mechanical properties (with a very high ratio between strength in compression and in tension), so that the applied loads do not diffuse as they do in elastic bodies, but tend to percolate along lines of high stiffness. Siege A siege ( Latin : sedere , lit.   'to sit') is a military blockade of

12400-428: The principal city from communicating with other cities where they might expect aid. Secondly, refugees from these smaller cities would flee to the last stronghold. The reports from these cities and the streaming hordes of refugees not only reduced the morale of the inhabitants and garrison of the principal city, it also strained their resources. Food and water reserves were taxed by the sudden influx of refugees. Soon, what

12524-502: The reason is probably because Chinese walls were already highly resistant to artillery and discouraged increasing the size of cannons. In the mid-twentieth century a European expert in fortification commented on their immensity: "in China ... the principal towns are surrounded to the present day by walls so substantial, lofty, and formidable that the medieval fortifications of Europe are puny in comparison." Chinese walls were thick. The eastern wall of Ancient Linzi , established in 859 BC, had

12648-566: The royal citadel or aristocratic compounds such as in Surakarta and Aceh . Large rammed earth walls were built in ancient China since the Shang dynasty ( c.  1600 –1050   BC), as 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

12772-434: The siege was of a location on a coastline, from ships launched from the harbor of the location. The universal method for defending against siege is the use of fortifications, principally walls and ditches , to supplement natural features. A sufficient supply of food and water was also important to defeat the simplest method of siege warfare: starvation . On occasion, the defenders would drive 'surplus' civilians out to reduce

12896-534: The size and number of cannon placements because the rooms could only be built so big. Notable surviving artillery towers include a seven layer defensive structure built in 1480 at Fougères in Brittany , and a four layer tower built in 1479 at Querfurth in Saxony. The star fort, also known as the bastion fort, trace italienne , or renaissance fortress, was a style of fortification that became popular in Europe during

13020-730: The tension force present in modern thin, light, tall building systems. Masonry has both structural and non-structural applications. Structural applications include walls, columns, beams, foundations, load-bearing arches, and others. On the other hand, masonry is also used in non-structural applications such as fireplaces chimneys and veneer systems. Brick and concrete block are the most common types of masonry in use in industrialized nations and may be either load-bearing or non-load-bearing. Concrete blocks, especially those with hollow cores, offer various possibilities in masonry construction. They generally provide great compressive strength and are best suited to structures with light transverse loading when

13144-634: The thickness of the walls in Beijing's Forbidden City were favoured by the Chinese Yongle Emperor (r. 1402–1424) because they were in pristine position to resist cannon volley and were built thick enough to withstand attacks from cannon fire. For more, see Technology of the Song dynasty . The introduction of gunpowder and the use of cannons brought about a new age in siege warfare. Cannons were first used in Song dynasty China during

13268-410: The top course of blocks in the walls filled with concrete and tied together with steel reinforcement to form a bond beam. Bond beams are often a requirement of modern building codes and controls. Another type of steel reinforcement referred to as ladder-reinforcement , can also be embedded in horizontal mortar joints of concrete block walls. The introduction of steel reinforcement generally results in

13392-546: The top of the walls occasionally had a roof. In addition to this, many different enhancements were made over the course of the centuries: The defensive towers of west and south European fortifications in the Middle Ages were often very regularly and uniformly constructed (cf. Ávila , Provins ), whereas Central European city walls tend to show a variety of different styles. In these cases the gate and wall towers often reach up to considerable heights, and gates equipped with two towers on either side are much rarer. Apart from having

13516-401: The use of deception or treachery to bypass defenses. Failing a military outcome, sieges can often be decided by starvation, thirst, or disease, which can afflict either the attacker or defender. This form of siege, though, can take many months or even years, depending upon the size of the stores of food the fortified position holds. The attacking force can circumvallate the besieged place, which

13640-597: The wall (called "header" bricks). Each row of bricks is known as a course. The pattern of headers and stretchers employed gives rise to different 'bonds' such as the common bond (with every sixth course composed of headers), the English bond, and the Flemish bond (with alternating stretcher and header bricks present on every course). Bonds can differ in strength and in insulating ability. Vertically staggered bonds tend to be somewhat stronger and less prone to major cracking than

13764-446: The wall. The morning came with most of our unit still behind us, but we were beyond the wall. Behind the gate great heaps of sandbags were piled up. We 'cleared them away, removed the lock, and opened the gates, with a great creaking noise. We'd done it! We'd opened the fortress! All the enemy ran away, so we didn't take any fire. The residents too were gone. When we passed beyond the fortress wall we thought we had occupied this city. As

13888-534: The walls of Babylon , reinforced by towers, moats, and ditches, gained a similar reputation. In Anatolia , the Hittites built massive stone walls around their cities atop hillsides, taking advantage of the terrain. In Shang dynasty China, at the site of Ao, large walls were erected in the 15th century BC that had dimensions of 20 m (66 ft) in width at the base and enclosed an area of some 1,900 m (2,100 yd) squared. The ancient Chinese capital for

14012-403: The walls of the marketplace of Chang'an were thicker than the walls of major European capitals. Aside from their immense size, Chinese walls were also structurally different from the ones built in medieval Europe. Whereas European walls were mostly constructed of stone interspersed with gravel or rubble filling and bonded by limestone mortar, Chinese walls had tamped earthen cores which absorbed

14136-534: The walls, and then deliberately collapsing or exploding the tunnel. This process is known as mining . The defenders could dig counter-tunnels to cut into the attackers' works and collapse them prematurely. Fire was often used as a weapon when dealing with wooden fortifications. The Roman Empire used Greek fire , which contained additives that made it hard to extinguish. Combined with a primitive flamethrower , it proved an effective offensive and defensive weapon. A sallying out might also occur with such weapons, or if

14260-413: The world. The construction of Egyptian pyramids, Roman aqueducts, and medieval cathedrals are all examples of masonry. Early structures used the weight of the masonry itself to stabilize the structure against lateral movements. The types and techniques of masonry used evolved with architectural needs and cultural norms. Since mid-20th century, masonry has often featured steel-reinforced elements to help carry

14384-595: Was "almost impervious to the efforts of horizontal fire." In fact twentieth century explosive shells had some difficulty creating a breach in tamped earthen walls. We fought our way to Nanking and joined in the attack on the enemy capital in December. It was our unit which stormed the Chunghua Gate. We attacked continuously for about a week, battering the brick and earth walls with artillery, but they never collapsed. The night of December 11, men in my unit breached

14508-656: Was achieved. Some popular tales existed on how the cunning heroes succeeded in their sieges. The best-known is the Trojan Horse of the Trojan War , and a similar story tells how the Canaanite city of Joppa was conquered by the Egyptians in the 15th century BC. The Biblical Book of Joshua contains the story of the miraculous Battle of Jericho . A more detailed historical account from the 8th century BC, called

14632-404: Was captured by stealthy attack. Alexander used commando-like tactics to scale the cliffs and capture the high ground, and the demoralized defenders surrendered. The importance of siege warfare in the ancient period should not be underestimated. One of the contributing causes of Hannibal 's inability to defeat Rome was his lack of siege engines , thus, while he was able to defeat Roman armies in

14756-434: Was developed for use by besieging armies. Ladders could be used to escalade over the defenses. Battering rams and siege hooks could also be used to force through gates or walls, while catapults , ballistae , trebuchets , mangonels , and onagers could be used to launch projectiles to break down a city's fortifications and kill its defenders. A siege tower , a substantial structure built to equal or greater height than

14880-587: Was not known at the time. In 1346, the bodies of Mongol warriors of the Golden Horde who had died of plague were thrown over the walls of the Crimean city of Kaffa (now Feodosiya ) during the Siege of Caffa . It has been speculated that this operation may have been responsible for the advent of the Black Death in Europe. The Black Death is estimated to have killed 30%–60% of Europe's population. On

15004-510: Was once a formidable undertaking became easy. The Mongols were then free to lay siege without interference of the field army, as it had been destroyed. At the siege of Aleppo , Hulagu used twenty catapults against the Bab al-Iraq ( Gate of Iraq ) alone. In Jûzjânî, there are several episodes in which the Mongols constructed hundreds of siege machines in order to surpass the number which the defending city possessed. While Jûzjânî surely exaggerated,

15128-446: Was refined during the rise of city-states , and energetic wall-building continued into the medieval period and beyond in certain parts of Europe. Simpler defensive walls of earth or stone, thrown up around hillforts , ringworks , early castles and the like, tend to be referred to as ramparts or banks. From very early history to modern times, walls have been a near necessity for every city. Uruk in ancient Sumer ( Mesopotamia )

15252-429: Was the greatest advantage enjoyed by the star fort. As a result, sieges lasted longer and became more difficult affairs. By the 1530s the bastion fort had become the dominant defensive structure in Italy. Outside Europe, the star fort became an "engine of European expansion," and acted as a force multiplier so that small European garrisons could hold out against numerically superior forces. Wherever star forts were erected

15376-437: Was to build relatively low and thick walls of packed earth, which could both withstand the force of cannon balls and support their own, defensive cannon. Chinese wall-building practice was, by happenstance, extremely resistant to all forms of battering. This held true into the twentieth century, when even modern explosive shells had some difficulty in breaking through tamped earth walls. The Chinese Wall Theory essentially rests on

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