Trebuchet
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.
There are two main types of trebuchets. The first is the traction trebuchet, or mangonel, which uses manpower to swing the arm. It first appeared in China in the 4th century BC. Carried westward by the Avars, the technology was adopted by the Byzantines in the late 6th century AD and by their neighbors in the following centuries.
The later, and often larger, counterweight trebuchet, also known as the counterpoise trebuchet, uses a counterweight to swing the arm. It appeared in both Christian and Muslim lands around the Mediterranean in the 12th century, and made its way back to China via Mongol conquests in the 13th century.
Terminology
Traction trebuchet and counterweight trebuchet are modern terms, not used by contemporary users of the weapons. The term traction trebuchet was created mainly to distinguish this type of weapon from the onager, a torsion powered catapult which is often conflated in contemporary sources with the mangonel, which was used as a generic term for any medieval stone throwing artillery. Both the traction and counterweight trebuchets have been called mangonel at one point or another. Confusion between the onager, mangonel, trebuchet and other catapult types in contemporary terminology has led some historians today to use the more precise traction trebuchet instead, with counterweight trebuchet used to distinguish what was before called simply a trebuchet. Some modern historians use mangonel to mean exclusively traction trebuchets, some call traction trebuchets traction mangonels, and counterweight trebuchets counterweight mangonels.The mangonel is called al-manjaniq in Arabic. In China the traction trebuchet was called the pao while the counterweight trebuchet was called the huihuipao.
Basic design
The trebuchet is a compound machine that makes use of the mechanical advantage of a lever to throw a projectile. They are typically large constructions, from in height to as much as three times that, made primarily of wood, usually reinforced with metal, leather, rope, and other materials. They are usually immobile and must be assembled on-site, possibly making use of local lumber with only key parts brought with the army to the site of the siege or battle.A trebuchet consists primarily of a long beam attached by an axle suspended high above the ground by a stout frame and base, such that the beam can rotate vertically through a wide arc. A sling is attached to one end of the beam to hold the projectile. The projectile is thrown when the beam is quickly rotated by applying force to the opposite end of the beam. The mechanical advantage is primarily obtained by having the projectile section of the beam much longer than the opposite section where the force is applied – usually four to six times longer.
The difference between counterweight and traction trebuchets is what force they use. Counterweight trebuchets use gravity; potential energy is stored by slowly raising an extremely heavy box attached to the shorter end of the beam, and releasing it on command. Traction trebuchets use human power; on command, men pull ropes attached to the shorter end of the trebuchet beam. The difficulties of coordinating the pull of many men together repeatedly and predictably makes counterweight trebuchets preferable for the larger machines, though they are more complicated to engineer. Further increasing their complexity is that either winches or treadwheels, aided by block and tackle, are typically required to raise the more massive counterweights. So while counterweight trebuchets require significantly fewer men to operate than traction trebuchets, they require significantly more time to reload. In a long siege, reload time may not be a critical concern.
When the trebuchet is operated, the force causes rotational acceleration of the beam around the axle. These factors multiply the acceleration transmitted to the throwing portion of the beam and its attached sling. The sling starts rotating with the beam, but rotates farther and therefore faster, transmitting this increased speed to the projectile. The length of the sling increases the mechanical advantage, and also changes the trajectory so that, at the time of release from the sling, the projectile is traveling in the desired speed and angle to give it the range to hit the target. Adjusting the sling's release point is the primary means of fine-tuning the range, as the rest of the trebuchet's actions are difficult to adjust after construction.
The rotation speed of the throwing beam increases smoothly, starting slow but building up quickly. After the projectile is released, the arm continues to rotate, allowed to smoothly slow down on its own accord and come to rest at the end of the rotation. This is unlike the violent sudden stop inherent in the action of other catapult designs such as the onager, which must absorb most of the launching energy into their own frame, and must be heavily built and reinforced as a result. This key difference makes the trebuchet much more durable, allowing for larger and more powerful machines.
A trebuchet projectile can be almost anything, even debris, rotting carcasses, or incendiaries, but is typically a large stone. Dense stone, or even metal, specially worked to be round and smooth, gives the best range and predictability. When attempting to breach enemy walls, it is important to use materials that will not shatter on impact; projectiles were sometimes brought from distant quarries to get the desired properties.
History
Traction trebuchet
The traction trebuchet, also referred to as a mangonel in some sources, is thought to have originated in ancient China. Torsion-based siege weapons such as the ballista and onager are not known to have been used in China.The first recorded use of traction trebuchets was in ancient China. They were probably used by the Mohists as early as 4th century BC, descriptions of which can be found in the Mojing. In Chapter 14 of the Mojing, the traction trebuchet is described hurling hollowed out logs filled with burning charcoal at enemy troops. Traction trebuchets went into decline during the Han dynasty due to long periods of peace but became a common siege weapon again during the Three Kingdoms period. They were used as ship mounted weapons by 573 for attacking enemy fortifications.
The trebuchet was carried westward by the Avars and appeared next in the eastern Mediterranean by the late 6th century AD, where it replaced torsion powered siege engines such as the ballista and onager due to its simpler design and faster rate of fire. The rapid replacement of previous siege engines was probably made possible by the deterioration of artillery expertise in the late Roman Empire. Evidence from Gaul and Germania suggests there was substantial loss of skills and techniques in artillery further west. The Byzantines adopted the traction trebuchet possibly as early as 587, the Persians in the early 7th century, and the Arabs in the second half of the 7th century. The Franks and Saxons adopted the weapon in the 8th century. Traction trebuchets were also used in India.
West of China, the traction trebuchet remained the primary siege weapon until the 12th century when it was replaced by the counterweight trebuchet. In China the traction trebuchet continued to be used until the counterweight trebuchet was introduced during the Mongol conquest of the Song dynasty. In 617 Li Mi constructed 300 trebuchets for his assault on Luoyang, in 621 Li Shimin did the same at Luoyang, and onward into the Song dynasty when in 1161, trebuchets operated by Song dynasty soldiers fired bombs of lime and sulphur against the ships of the Jin dynasty navy during the Battle of Caishi.
Hand-trebuchet
The hand-trebuchet was a staff sling mounted on a pole using a lever mechanism to propel projectiles. Basically a one-man traction trebuchet, it was used by emperor Nikephoros II Phokas around 965 to disrupt enemy formations in the open field. It was also mentioned in the Taktika of general Nikephoros Ouranos, and listed in De obsidione toleranda as a form of artillery.Hybrid trebuchet
According to Paul E. Chevedden, a hybrid trebuchet existed that used both counterweight and human propulsion. However no illustrations or descriptions of the device exist from the time when they were supposed to have been used. The entire argument for the existence of hybrid trebuchets rests on accounts of increasingly more effective siege weapons. Peter Purton suggests that this was simply because the machines became larger. The earliest depiction of a hybrid trebuchet is dated to 1462, when trebuchets had already become obsolete due to cannons.Counterweight trebuchet
The counterweight trebuchet has been described as the "most powerful weapon of the Middle Ages."The earliest known description and illustration of a counterweight trebuchet comes from a commentary on the conquests of Saladin by Mardi ibn Ali al-Tarsusi in 1187. However cases for the existence of both European and other Muslim trebuchets prior to 1187 have been made. In 1090, Khalaf ibn Mula'ib threw out a man from the citadel in Salamiya with a machine and in the early 12th century, Muslim siege engines were able to breach crusader fortifications. David Nicolle argues that these events could have only been possible with the use of counterweight trebuchets.
Paul E. Chevedden argues that counterweight trebuchets appeared prior to 1187 in Europe based on what might have been counterweight trebuchets in earlier sources. The 12th-century Byzantine historian Niketas Choniates may have been referring to a counterweight trebuchet when he described one equipped with a windlass, which is only useful to counterweight machines, at the siege of Zevgminon in 1165. At the Siege of Nicaea in 1097 the Byzantine emperor Alexios I Komnenos reportedly invented new pieces of heavy artillery which deviated from the conventional design and made a deep impression on everyone. Possible references to counterweight trebuchets also appear for the second siege of Tyre in 1124, where the crusaders reportedly made use of "great trebuchets". Chevedden argues that given the references to new and better trebuchets that by the 1120–30s, the counterweight trebuchet was being used in a variety of places by different peoples such as the crusader states, the Normans of Sicily and the Seljuks.
The earliest solid reference to counterweight trebuchets in European sources dates to the siege of Castelnuovo Bocca d'Adda in 1199. They were used in Germany from around 1205, in England at least by 1217, and in Iberia shortly after 1218. By the 1230s the counterweight trebuchet was a common item in siege warfare.
Counterweight trebuchets do not appear with certainty in Chinese historical records until about 1268 when the Mongols laid siege to Fancheng and Xiangyang. After failing to take the twin cities of Fancheng and Xiangyang for several years, collectively known as the Siege of Fancheng and Xiangyang, the Mongol army brought in two Persian engineers to build hinged counterweight trebuchets. Known as the Huihui trebuchet, or Xiangyang trebuchet because they were first encountered in that battle. Ismail and Al-aud-Din travelled to South China from Iraq and built trebuchets for the siege. Chinese and Muslim engineers operated artillery and siege engines for the Mongol armies. By 1283, counterweight trebuchets were also used in Southeast Asia by the Chams against the Yuan dynasty.
The counterweight trebuchet did not completely replace the traction trebuchet. Despite its greater range, counterweight trebuchets had to be constructed close to the site of the siege unlike traction trebuchets, which were smaller, lighter, cheaper, and easier to take apart and put back together again where necessary. The superiority of the counterweight trebuchet was not clear cut. Of this, the Hongwu Emperor stated in 1388: "The old type of trebuchet was really more convenient. If you have a hundred of those machines, then when you are ready to march, each wooden pole can be carried by only four men. Then when you reach your destination, you encircle the city, set them up, and start shooting!" The traction trebuchet continued to serve as an anti-personnel weapon. The Norwegian text of 1240, Speculum regale, explicitly states this division of functions. Traction trebuchets were to be used for hitting people in undefended areas. There is evidence that the counterweight trebuchet could be transported, as shown in two 17th- and 18th-century Chinese illustrations, which are also the only Chinese depictions of counterweight trebuchets on land. According to Liang Jieming, the "illustration shows... its throwing arm disassembled, its counterweight locked with supporting braces, and prepped for transport and not in battle deployment." However according to Joseph Needham, the large tank in the middle is the counterweight, while the bulb at the end of the arm was for adjusting between fixed and swinging counterweights. Both Liang and Needham note that the illustrations are poorly drawn and confusing, leading to mislabeling.
The counterweight and traction trebuchets were phased out around the mid-15th century in favor of gunpowder weapons.
Couillard
The couillard is a smaller version of a counterweight trebuchet with a single frame instead of the usual double "A" frames. The counterweight is split into two halves to avoid hitting the center frame.Decline of military use
With the introduction of gunpowder, the trebuchet began to lose its place as the siege engine of choice to the cannon. Trebuchets were still used both at the siege of Burgos and siege of Rhodes. One of the last recorded military uses was by Hernán Cortés, at the 1521 siege of the Aztec capital Tenochtitlán. Accounts of the attack note that its use was motivated by the limited supply of gunpowder. The attempt was reportedly unsuccessful: the first projectile landed on the trebuchet itself, destroying it.In China, the last time trebuchets were seriously considered for military purposes was in 1480. Not much is heard of them afterwards.
Comparison of different artillery weapons
Roman torsion engines
Chinese trebuchets
Siege crossbows
Reconstructed traction trebuchets
Reconstructed counterweight trebuchets
Modern use
Recreation and education
Most trebuchet use in recent centuries has been for recreational or educational, rather than military purposes. New machines have been constructed and old ones restored by living history enthusiasts, for historical re-enactments, and use in other historical celebrations. As their construction is substantially simpler than modern weapons, trebuchets also serve as the object of engineering challenges.The trebuchet's technical constructions were lost at the beginning of the 16th century. In 1984, the French engineer Renaud Beffeyte made the first modern reconstruction of a trebuchet, based on documents from 1324.
The largest currently-functioning trebuchet in the world is the 22-tonne machine at Warwick Castle, England, constructed in 2005. Based on historical designs, it stands tall and throws missiles typically 36 kg up to. The trebuchet gained significant interest from numerous news sources when in 2015 a burning missile fired from the siege engine struck and damaged a Victorian-era boathouse situated at the River Avon close by, inadvertently demonstrating the weapon's power. It is built on the design of a similar trebuchet at Middelaldercentret in Denmark. In 1989, Middelaldercentret became the first place in the modern era to have a working trebuchet.
Trebuchets compete in one of the classifications of machines used to hurl pumpkins at the annual pumpkin chucking contest held in Sussex County, Delaware, U.S. The record-holder in that contest for trebuchets is the Yankee Siege II from New Hampshire, which at the 2013 WCPC Championship tossed a pumpkin 2835.8 ft. The, trebuchet flings the standard pumpkins, specified for all entries in the WCPC competition.
A large trebuchet was tested in late 2017 in Belfast as part of the set for the television series Game of Thrones.
A large trebuchet based on Edward I's "Warwolf" was constructed for a scene in David Mackenzie's movie Outlaw King about Robert the Bruce, King of Scots. During the film, it hurls an incendiary projectile at Stirling Castle. It recreates the true story that it took some three months to build, and Edward I "Longshanks" would not let his enemy surrender until he could use it.
Developments
Although rarely used as a weapon today, trebuchets maintain the interest of professional and hobbyist engineers. One modern technological development, especially for the competitive pumpkin-hurling events, is the "floating arms" design. Instead of using the traditional axle fixed to a frame, these devices are mounted on wheels that roll on a track parallel to the ground, with a counterweight that falls directly downward upon release, allowing for greater efficiency by increasing the proportion of energy transferred to the projectile. A more radical design; Jonathan, Orion, and Emmerson Stapleton's "walking arm", described as "...a stick falling over with a huge counterweight on top of the stick..." debuted in 2016 and in 2018 won both the Grand Champion Best Design and Middleweight Open Division of the 10th annual Vermont Pumpkin Chuckin Festival.Uses in activism and insurgency
In 2013, during the Syrian civil war, rebels were filmed using a trebuchet in the Battle of Aleppo. The trebuchet was used to project explosives at government troops.In 2014, during the Hrushevskoho street riots in Ukraine, rioters used an improvised trebuchet to throw bricks and molotov cocktails at the Berkut.