A trebuchet () is a type of catapult that uses a hinged arm with a sling attached to the tip to launch 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 weight and/or at greater range than a traditional catapult.
There are two main types of trebuchet. The first is the traction trebuchet, or mangonel, which uses manpower to swing the arm. It first appeared in China by the 4th century BC. It spread westward, possibly via the Avars, and was adopted by the Byzantines, Persians, Arabs, and other neighboring peoples by the sixth to seventh centuries AD. "Another, more specifically Chinese contribution to military technology that may have been carried westward by the Avars is the traction trebuchet. In contrast to the counterweighted trebuchet..."
The later, and often larger and more powerful, 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 was carried back to China by the Mongols in the 13th century. "Although this is strong evidence that this type of technology was known, and likely employed, in the Levant before the first known use of 'trebuchet', there is little consensus among scholars as to when and where the counterweight trebuchet was first developed. Al-Tarsusi's description and accompanying illustration are far from conclusive proof that this type of engine was developed in the Islamic world. At the siege of Acre in 1189-91, eyewitness sources provide no indication that the artillery employed by either the Muslim garrison or the crusaders was superior."
Etymology and terminology
The numerous forms of the word that appeared during the 13th century, including trabocco, tribok, tribuclietta, and trubechetum, have obscured the origin of the term. In Arabic the counterweight trebuchet was called manjaniq maghribi or majaniq ifranji. In China, the traction trebuchet was called the pào (砲) while the counterweight trebuchet was called the húihúi pào (回回砲, Muslim trebuchet).
The English word trebuchet is first mentioned in the 14th century (13th century in Anglo-Latin) as "medieval stone-throwing engine of war".Etymology Online : trebuchet It is borrowed from (Old) French trebuchet (now trébuchet).
The French word is from the verbal root of trebucher (now trébucher) : trebuch- + diminutive noun suffix -et, trebucher (10th century) meant "to overthrow, to bring down", then and now "to stumble",CNRTL : trébucher (read online in French) maybe earlier "to rock" or "to tilt". It is a compound of (Old) French tre(s)-, variant form tra- (now tré- / tra-) from Latin trans expressing "displacement" in that case + Old French buc "trunk of the body, bulk", itself from Old Low Franconian *būk- "belly" similar to Old High German buh, German Bauch "belly".
The earliest appearance of the term "trebuchet" in French dates to the late 12th century and the first attestations of trebuchet as a siege weapon are from around the year 1200. The 1174–1177 edition of Roman de Renart, an epic about Renard the Fox, describes it as a "trap whose trigger mechanism consists of an assembly of balanced logs" (understood as animal trap by 1375) while the edition describes it as a "war engine that throws stones to break down walls".CNRTL : trébuchet (read online in French)Dictionnaire historique de la langue française, sous la direction d'Alain Rey, Editions Le Robert, p. 3738b The word trabuchellus appeared alongside manganum and prederia in a document in Vicenza on . Trabucha is found a decade later with predariae at the siege of Castelnuovo Bocca d'Adda in an account by Iohannes Codagnellus. It is unclear, however, whether these referred to counterweight trebuchets. Codagnellus did not specify a specific type of engine with the term and even implied that they were "fairly light in subsequent references". Only in the late 1210s do variations of "trebuchet" in sources, described as increasingly powerful machines or utilizing different components, identify more closely with the counterweight trebuchet. Other terms, such as machina maior/magna, might have also referred to counterweight trebuchets.
Traction trebuchet and counterweight trebuchet are modern terms (retronyms), 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 that 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, while others call traction trebuchets traction mangonels and counterweight trebuchets counterweight mangonels.
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, with the length of the beam as much as , with some purported to be even larger.
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 (typically over 180°). 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 be 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 (typically filled with stones, sand, or lead) attached to the shorter end of the beam (typically on a hinged connection), and releasing it on command.
Traction trebuchets use human power; on command, people pull ropes attached to the shorter end of the trebuchet beam. The difficulties of coordinating the pull of many people together repeatedly and predictably makes counterweight trebuchets preferable for the larger machines, though they are more complicated to engineer. The trebuchet had further modifications to allow an increase to its range, by creating a slot for the sling and projectile to sit underneath the trebuchet, enabling the sling to be lengthened and thus extending the range, an alteration in the trajectory, or the release point to be changed. 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 people 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 (the fulcrum of the lever). 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 (typically about 360°) 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, originated in ancient China. "The earliest version of the trebuchet, which worked on the principle of a pivoted beam, that is, the man-powered traction trebuchet, was operated by a crew pulling on ropes, which were attached to the short end of the beam, in other words by using manpower rather than a counterweight. Such machines date back as far as ancient China." "The trebuchet, invented in China between the fifth and third centuries B.C.E., reached the Mediterranean by the sixth century C.E.". "The traction trebuchet, invented by the Chinese sometime before the fourth century B.C." "With regard to stone-throwers, however, China and the Mediterranean world had followed quite different paths of development. Hellenistic and Roman stone-throwers were torsion machines that derived their propulsive power from twisted fibers or sinews, whereas in China, as we have seen, traction-based stone-throwers (or trebuchets) had been employed since ancient times and torsion-based devices are not attested. There has been much debate about whether even the simplest of the torsion machines, the one-armed "onager," remained in use into the early Byzantine period. But the dominant trend was toward convergence, with the Byzantines adopting the traction trebuchet as their new stone-thrower (and possibly as early as 587)."