Siege engine

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Replica battering ram at Chateau des Baux, France Battering ram.jpg
Replica battering ram at Château des Baux, France

A siege engine is a device that is designed to break or circumvent heavy castle doors, thick city walls and other fortifications in siege warfare. Some are immobile, constructed in place to attack enemy fortifications from a distance, while others have wheels to enable advancing up to the enemy fortification. There are many distinct types, such as siege towers that allow foot soldiers to scale walls and attack the defenders, battering rams that damage walls or gates, and large ranged weapons (such as ballistae, catapults/trebuchets and other similar constructions) that attack from a distance by launching projectiles. Some complex siege engines were combinations of these types.


Siege engines are fairly large constructions – from the size of a small house to a large building. From antiquity up to the development of gunpowder, they were made largely of wood, using rope or leather to help bind them, possibly with a few pieces of metal at key stress points. They could launch simple projectiles using natural materials to build up force by tension, torsion, or, in the case of trebuchets, human power or counterweights coupled with mechanical advantage. With the development of gunpowder and improved metallurgy, bombards and later heavy artillery became the primary siege engines.

Collectively, siege engines or artillery together with the necessary soldiers, sappers, ammunition, and transport vehicles to conduct a siege are referred to as a siege train. [1]


Ancient Assyria through the Roman Empire

Siege engine in Assyrian relief of attack on an enemy town during the reign of Tiglath-Pileser III 743-720 BC from his palace at Kalhu (Nimrud) Assyrian relief of attack on an enemy town during the reign of Tiglath-Pileser III 720-743 BCE from his palace at Kalhu (Nimrud).jpg
Siege engine in Assyrian relief of attack on an enemy town during the reign of Tiglath-Pileser III 743-720 BC from his palace at Kalhu (Nimrud)

The earliest siege engines appear to be simple movable roofed towers used for cover to advance to the defenders' walls in conjunction with scaling ladders, depicted during the Middle Kingdom of Egypt. [2] Advanced siege engines including battering rams were used by Assyrians, followed by the catapult in ancient Greece. In Kush siege towers as well as battering rams were built from the 8th century and employed in Kushite siege warfare, such as the siege of Ashmunein in 715 BC. [3] [4] The Spartans used battering rams in the Siege of Plataea in 429 BC, but it seems that the Greeks limited their use of siege engines to assault ladders, though Peloponnesian forces used something resembling flamethrowers.

The first Mediterranean people to use advanced siege machinery were the Carthaginians, who used siege towers and battering rams against the Greek colonies of Sicily. These engines influenced the ruler of Syracuse, Dionysius I, who developed a catapult in 399 BC. [5]

The first two rulers to make use of siege engines to a large extent were Philip II of Macedonia and Alexander the Great. Their large engines spurred an evolution that led to impressive machines, like the Demetrius Poliorcetes' Helepolis (or "Taker of Cities") of 304 BC: nine stories high and plated with iron, it stood 40 m (130 ft) tall and 21 m (69 ft) wide, weighing 180 t (400,000 lb). The most used engines were simple battering rams, or tortoises, propelled in several ingenious ways that allowed the attackers to reach the walls or ditches with a certain degree of safety. For sea sieges or battles, seesaw-like machines (sambykē or sambuca) were used. These were giant ladders, hinged and mounted on a base mechanism and used for transferring marines onto the sea walls of coastal towns. They were normally mounted on two or more ships tied together and some sambykē included shields at the top to protect the climbers from arrows. Other hinged engines were used to catch enemy equipment or even opposing soldiers with opposable appendices which are probably ancestors to the Roman corvus. Other weapons dropped heavy weights on opposing soldiers.[ citation needed ]

Roman siege engines. Roman siege machines.gif
Roman siege engines.

The Romans preferred to assault enemy walls by building earthen ramps (agger) or simply scaling the walls, as in the early siege of the Samnite city of Silvium (306 BC). Soldiers working at the ramps were protected by shelters called vineae, that were arranged to form a long corridor. Convex wicker shields were used to form a screen ( plutei or plute in English) [6] to protect the front of the corridor during construction of the ramp. [7] Another Roman siege engine sometimes used resembled the Greek ditch-filling tortoise,[ clarification needed ] called a musculus ("muscle"). Battering rams were also widespread. The Roman Legions first used siege towers around 200 BC; in the first century BC, Julius Caesar accomplished a siege at Uxellodunum in Gaul using a ten-story siege tower. [7] Romans were nearly always successful in besieging a city or fort, due to their persistence, the strength of their forces, their tactics, and their siege engines. [7]

The first documented occurrence of ancient siege artillery pieces in Europe was the gastraphetes ("belly-bow"), a kind of large crossbow. These were mounted on wooden frames. Greater machines forced the introduction of pulley system for loading the projectiles, which had extended to include stones also. Later torsion siege engines appeared, based on sinew springs. The onager was the main Roman invention in the field.

A stone-throwing machine set to defend a gate, in the fresco of Guidoriccio da Fogliano by Simone Martini (14th century). Guidoriccio mangonel.jpg
A stone-throwing machine set to defend a gate, in the fresco of Guidoriccio da Fogliano by Simone Martini (14th century).

Ancient China

The earliest documented occurrence of ancient siege-artillery pieces in China was the levered principled traction catapult and an 8 ft (2.4 m) high siege crossbow from the Mozi (Mo Jing), a Mohist text written at about the 4th – 3rd century BC by followers of Mozi who founded the Mohist school of thought during the late Spring and Autumn period and the early Warring States period. Much of what we now know of the siege technology of the time comes from Books 14 and 15 (Chapters 52 to 71) on Siege Warfare from the Mo Jing. Recorded and preserved on bamboo strips, much of the text is now extremely corrupted. However, despite the heavy fragmentation, Mohist diligence and attention to details which set Mo Jing apart from other works ensured that the highly descriptive details of the workings of mechanical devices like Cloud Ladders, Rotating Arcuballistas and Levered Catapults, records of siege techniques and usage of siege weaponry can still be found today. [8]


Chinese, Indian, Sri Lankan and Southeast Asian kingdoms used war elephants as siege engines too.

Middle Ages

The medieval Mons Meg with its 20" (50 cm) cannonballs MonsMeg.JPG
The medieval Mons Meg with its 20" (50 cm) cannonballs

Medieval designs include a large number of catapults such as the mangonel, onager, the ballista, the traction trebuchet (first designed in China in the 3rd century BC and brought over to Europe in the 4th century AD), and the counterweight trebuchet (first described by Mardi bin Ali al-Tarsusi in the 12th century, though of unknown origin). These machines used mechanical energy to fling large projectiles to batter down stone walls. Also used were the battering ram and the siege tower, a wooden tower on wheels that allowed attackers to climb up and over castle walls, while protected somewhat from enemy arrows.

A typical military confrontation in medieval times was for one side to lay siege to an opponent's castle. When properly defended, they had the choice whether to assault the castle directly or to starve the people out by blocking food deliveries, or to employ war machines specifically designed to destroy or circumvent castle defenses. Defending soldiers also used trebuchets and catapults as a defensive advantage.

Other tactics included setting fires against castle walls in an effort to decompose the cement that held together the individual stones so they could be readily knocked over. Another indirect means was the practice of mining, whereby tunnels were dug under the walls to weaken the foundations and destroy them. A third tactic was the catapulting of diseased animals or human corpses over the walls in order to promote disease which would force the defenders to surrender, an early form of biological warfare.

Modern era

One of the super-heavy Karl-Gerat siege mortars used by the German army in World War II Karl6.jpg
One of the super-heavy Karl-Gerät siege mortars used by the German army in World War II
A German Big Bertha howitzer being readied for firing Dicke Bertha.Big Bertha.jpg
A German Big Bertha howitzer being readied for firing

With the advent of gunpowder, firearms such as the arquebus and cannon—eventually the petard, mortar and artillery—were developed. These weapons proved so effective that fortifications, such as city walls, had to be low and thick, as exemplified by the designs of Vauban.

The development of specialized siege artillery, as distinct from field artillery, culminated during World War I and World War II. During the First World War, huge siege guns such as Big Bertha were designed to see use against the modern fortresses of the day. The apex of siege artillery was reached with the German Schwerer Gustav gun, a huge 800 mm (31 in) caliber railway gun, built during early World War II. Schwerer Gustav was initially intended to be used for breaching the French Maginot Line of fortifications, but was not finished in time and (as a sign of the times) the Maginot Line was circumvented by rapid mechanized forces instead of breached in a head-on assault. The long time it took to deploy and move the modern siege guns made them vulnerable to air attack and it also made them unsuited to the rapid troop movements of modern warfare.

See also

Related Research Articles

Catapult Pre-gunpowder projectile-launching device

A catapult is a ballistic device used to launch a projectile a great distance without the aid of gunpowder or other propellants – particularly various types of ancient and medieval siege engines. A catapult uses the sudden release of stored potential energy to propel its payload. Most convert tension or torsion energy that was more slowly and manually built up within the device before release, via springs, bows, twisted rope, elastic, or any of numerous other materials and mechanisms.

Medieval warfare History and description of warfare in the European Middle Ages

Medieval warfare is the European warfare of the Middle Ages. Technological, cultural, and social developments had forced a severe transformation in the character of warfare from antiquity, changing military tactics and the role of cavalry and artillery. In terms of fortification, the Middle Ages saw the emergence of the castle in Europe, which then spread to the Holy Land.

Siege Military land blockade of a location

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 Latin: sedere, lit. 'to sit'. Siege warfare is a form of constant, low-intensity conflict characterized by one party holding a strong, static, defensive position. Consequently, an opportunity for negotiation between combatants is not uncommon, as proximity and fluctuating advantage can encourage diplomacy. The art of conducting and resisting sieges is called siege warfare, siegecraft, or poliorcetics.

Siege tower Mobile structure for attacking walls

A siege tower or breaching tower is a specialized siege engine, constructed to protect assailants and ladders while approaching the defensive walls of a fortification. The tower was often rectangular with four wheels with its height roughly equal to that of the wall or sometimes higher to allow archers to stand on top of the tower and shoot arrows into the fortification. Because the towers were wooden and thus flammable, they had to have some non-flammable covering of iron or fresh animal skins.

Battering ram Siege engine originating in ancient times

A battering ram is a siege engine that originated in ancient times and was designed to break open the masonry walls of fortifications or splinter their wooden gates. In its simplest form, a battering ram is just a large, heavy log carried by several people and propelled with force against an obstacle; the ram would be sufficient to damage the target if the log were massive enough and/or it were moved quickly enough. Later rams encased the log in an arrow-proof, fire-resistant canopy mounted on wheels. Inside the canopy, the log was swung from suspensory chains or ropes.

Ballista Ancient ranged weapon

The ballista, plural ballistae, sometimes called bolt thrower, was an ancient missile weapon that launched either bolts or stones at a distant target.

Trebuchet Siege engine using long arm to throw projectiles

A trebuchet is a type of catapult that uses a long arm to throw a projectile. It was a common powerful siege engine until the advent of gunpowder. The design of a trebuchet allows it to launch projectiles of greater weights further distances than that of a traditional catapult.

The Battle of Xiangyang was a protracted series of battles between the invading Mongols of the Yuan dynasty and Chinese Southern Song forces from AD 1267 to 1273. The battle was a significant victory for the Mongol Empire and ended a 30 year defensive campaign waged by the Song dynasty, allowing the Mongols to advance into the Chinese heartland. The capture of Xiangyang also allowed the Mongols to take control of the Han and Yangtze rivers, thereby depriving the Song dynasty of two formidable natural barriers. The defeat devastated the Song dynasty, which collapsed several years later at the Battle of Yamen.

Mangonel Human-powered trebuchet

The mangonel, also called the traction trebuchet, was a type of trebuchet or siege engine used in Ancient China starting from the Warring States period, and later across Eurasia by the 6th century AD. Unlike the earlier torsion engines and later counterweight trebuchet, the mangonel operated on manpower pulling cords attached to a lever and sling to launch projectiles. Although the mangonel required more men to function, it was also less complex and faster to reload than the torsion-powered ballista and onager which it replaced in early Medieval Europe. It was replaced as the primary siege weapon in the 12th and 13th centuries by the counterweight trebuchet. A common misconception about the mangonel is that it was a torsion siege engine, which it is often depicted as in modern times, despite all evidence to the contrary.

Early thermal weapons Weapons during the classical and medieval periods that used heat or burning for damage

Early thermal weapons were used in warfare during the classical and medieval periods using heat or burning action to destroy or damage enemy personnel, fortifications or territories.

Roman siege engines were, for the most part, adapted from Hellenistic siege technology. Relatively small efforts were made to develop the technology; however, the Romans brought an unrelentingly aggressive style to siege warfare that brought them repeated success. Up to the first century BC, the Romans utilized siege weapons only as required and relied for the most part on ladders, towers and rams to assault a fortified town. Ballistae were also employed, but held no permanent place within a legion's roster, until later in the republic, and were used sparingly. Julius Caesar took great interest in the integration of advanced siege engines, organizing their use for optimal battlefield efficiency.

Helepolis Siege engine

Helepolis is the Greek name for a movable siege tower.

The Sasanian army was the primary military body of the Sasanian armed forces, serving alongside the Sasanian navy. The birth of the army dates back to the rise of Ardashir I, the founder of the Sasanian Empire, to the throne. Ardashir aimed at the revival of the Persian Empire, and to further this aim, he reformed the military by forming a standing army which was under his personal command and whose officers were separate from satraps, local princes and nobility. He restored the Achaemenid military organizations, retained the Parthian cavalry model, and employed new types of armour and siege warfare techniques. This was the beginning for a military system which served him and his successors for over 400 years, during which the Sasanian Empire was, along with the Roman Empire and later the East Roman Empire, one of the two superpowers of Late Antiquity in Western Eurasia. The Sasanian army protected Eranshahr from the East against the incursions of central Asiatic nomads like the Hephthalites and Turks, while in the west it was engaged in a recurrent struggle against the Roman Empire.

A lithobolos refers to any mechanical artillery weapon used and/or referred to as a stone thrower in ancient warfare. Typically this referred to engines that propel a stone along a flat track with two rigid bow arms powered by torsion, in particular all sizes of palintonon.

Torsion siege engine Type of artillery relying on a twisting force to launch projectiles

A torsion siege engine is a type of artillery that utilizes torsion to launch projectiles. They were initially developed by the ancient Macedonians, specifically Philip II of Macedon and Alexander the Great, and used through the Middle Ages until the development of gunpowder artillery in the 14th century rendered them obsolete.

History of weapons Aspect of history

People have used weapons in warfare, hunting, self-defense, law enforcement, and criminal activity. Weapons also serve many other purposes in society including use in sports, collections for display, and historical displays and demonstrations. As technology has developed throughout history, weapons have changed with it.

The Greeks and Romans both made extensive use of artillery for shooting large arrows, bolts or spherical stones or metal balls. Occasionally they also used ranged early thermal weapons. There was heavy siege artillery, but more mobile and lighter field artillery was already known and used in pitched battles, especially in Roman imperial period.

Chinese siege weapons

This is an overview of Chinese siege weapons.


  1. "Siege train" on
  2. "Siege warfare in ancient Egypt". Tour Egypt. Retrieved 23 May 2020.
  3. Dodson, Aidan (1996). Monarchs of the nile. 1. ISBN   978-97-74-24600-5.
  4. "Siege warfare in ancient Egypt". Tour Egypt. Retrieved 23 May 2020.
  5. "The Catapult: A History", Tracy Rihall, 2007
  6. An obsolete English synonym for "pluteus" is "plute". "plute" . Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  7. 1 2 3 Cartwright, Mark (24 June 2016). "Roman Siege Warfare". World History Encyclopedia . Retrieved 19 January 2018.
  8. Liang, Jieming (2006). Chinese Siege Warfare: Mechanical Artillery & Siege Weapons of Antiquity, pp. Appendix D