The trebuchet is a gravity- or manpower-powered medieval siege engine that uses a long lever and sling to hurl projectiles. Originating in China and spreading across Eurasia by late antiquity, it became the dominant artillery for breaching fortifications in the Middle Ages until superseded by gunpowder cannon. Its mechanics and historical use have been documented by historians and engineers, with modern reconstructions illuminating its range, payload, and efficiency.
Last updated October 3, 2025
The trebuchet is a lever-and-sling siege engine designed to throw heavy missiles for breaching walls and bombarding targets during Siege warfare. It was widely used across the Middle Ages after originating in China and diffusing westward, ultimately becoming the most powerful pre-gunpowder artillery in Eurasia. Encyclopaedia Britannica; Scientific American.
Etymology and definition
The English word “trebuchet” derives from Old French trébuchet, related to trébucher “to overthrow; to stumble,” and appears in medieval Latin as trebuchetum; the term denotes a stone‑throwing engine. Merriam‑Webster; Etymonline. A trebuchet is defined by a long arm pivoting on a high axle with a sling at the long end and either a counterweight or a rope team at the short end. Encyclopaedia Britannica.
Origins and diffusion
Traction (man‑powered) trebuchets appear in Chinese sources between the 5th and 3rd centuries BCE and had spread to the Mediterranean by the 6th century CE. Encyclopaedia Britannica; Scientific American. From late antiquity into the early medieval period, traction machines replaced torsion artillery such as the onager in many regions due to simpler construction and safer operation. Scientific American.
Counterweight trebuchets emerged in the central and western Mediterranean by the 12th–13th centuries and rapidly transformed siegecraft with greater range and projectile mass. Dumbarton Oaks Papers—Chevedden; (book://Peter Purton|A History of the Late Medieval Siege 1200–1500|Boydell|2009). During the Mongol expansions, engineers from the Islamic world introduced counterweight machines—known in Chinese as huihui pao—to East Asia in the 13th century, notably at the sieges of Fancheng–Xiangyang (1273), accelerating their adoption in Yuan China and beyond. (book://Joseph Needham & Robin Yates|Science and Civilisation in China, Vol. 5, Part 6: Military Technology: Missiles and Sieges|Cambridge University Press|1994); Encyclopaedia Britannica.
Design and mechanics
All trebuchets exploit the mechanical advantage of a lever with a long projectile arm and short power arm; upon release, the short arm descends and the sling whips the payload into a high‑energy ballistic trajectory. Encyclopaedia Britannica. In counterweight versions, gravitational potential energy is stored by raising a massive weight (often stones, sand, or lead) attached to the short arm; in traction versions, teams pull ropes attached to that arm. Encyclopaedia Britannica; Scientific American.
Medieval engineers recognized and modern tests confirm that hinged (swinging) counterweights permit a near‑vertical drop, improving energy transfer compared with fixed counterweights. PBS NOVA; Scientific American. Numerical and experimental studies of trebuchet dynamics further detail the roles of the arm, counterweight, and sling in optimizing range. The Physics Teacher (AIP); arXiv.
Performance varied with scale and design. Estimates and records report large trebuchets hurling roughly 60‑kg projectiles to about 350 m, and some machines capable of casting stones of several hundred kilograms. Encyclopaedia Britannica. Contemporary reconstructions similarly demonstrate long ranges with heavy payloads when properly tuned. PBS NOVA.
Types and terminology
–Traction trebuchet (often called “mangonel” in some medieval Latin/vernacular sources): powered by coordinated pullers on ropes attached to the short arm; common before widespread counterweight adoption. Scientific American; (book://Peter Purton|A History of the Late Medieval Siege 1200–1500|Boydell|2009).
–Counterweight trebuchet: uses a fixed, hanging, or hinged mass; the hinged type generally showed superior range and efficiency. PBS NOVA; Scientific American.
Operational use
Trebuchets were used to batter curtain walls, topple merlons and towers, interdict works and gates, and deliver incendiaries or other munitions. Encyclopaedia Britannica. In the 13th century, the Mongol Empire fielded powerful counterweight engines—constructed and operated by Islamic engineers—during protracted sieges against the Song dynasty fortresses of Fancheng and Xiangyang, where long‑range, accurate fire played a decisive role. (book://Joseph Needham & Robin Yates|Science and Civilisation in China, Vol. 5, Part 6|Cambridge University Press|1994); Encyclopaedia Britannica.
In western Europe, a famous exemplar was “Warwolf,” assembled for Edward I at the siege of Stirling Castle in 1304; documentary and analytical studies indicate an immense timber structure capable of hurling very large stones, with modern estimates placing its overall height with arm extended at roughly 90 m. Guinness World Records; Journal of Medieval Military History (Boydell/Cambridge).
Although gunpowder artillery gradually eclipsed mechanical engines from the 15th century, trebuchets continued to appear where powder or guns were scarce; one of the last noted wartime uses was an attempted deployment by Hernán Cortés during the siege of Tenochtitlán in 1521. Encyclopaedia Britannica.
Munitions and special uses
Beyond stone shot, crews launched incendiaries, pots of combustible mixtures, and occasionally noxious or biological materials. Encyclopaedia Britannica. The often‑cited episode at the 1346 siege of Caffa describes plague‑stricken corpses hurled into the city; scholarly assessment deems such an attack plausible but debates its broader epidemiological significance. Emerging Infectious Diseases (CDC); Bulletin of the Atomic Scientists. The association of siege hurling and disease later became part of narratives about the spread of the Black Death, though modern studies caution against overgeneralization. Emerging Infectious Diseases (CDC); Bulletin of the Atomic Scientists.
Knowledge, science, and craft
Trebuchet building drew on practical carpentry, rigging, and empirical tuning of sling length, release angle, and counterweight mass. Scientific American. Historians have argued that observing hinged‑counterweight motion and lever mechanics informed medieval discussions of statics and positional gravity associated with Jordanus de Nemore; the machine also appears in broader histories of technology as a significant application of gravitational energy. Encyclopaedia Britannica; Dumbarton Oaks Papers—Chevedden.
Legacy and reconstruction
Modern experimental archaeology and educational engineering routinely reconstruct trebuchets, from small classroom kits to large outdoor engines, to study energy transfer, ballistics, and structural design. PBS NOVA; The Physics Teacher (AIP). Public displays and competitive events continue to demonstrate the trebuchet’s capabilities while offering insight into pre‑modern military engineering. Guinness World Records.
The trebuchet is a gravity- or manpower-powered medieval siege engine that uses a long lever and sling to hurl projectiles. Originating in China and spreading across Eurasia by late antiquity, it became the dominant artillery for breaching fortifications in the Middle Ages until superseded by gunpowder cannon. Its mechanics and historical use have been documented by historians and engineers, with modern reconstructions illuminating its range, payload, and efficiency.
Last updated October 3, 2025
The trebuchet is a lever-and-sling siege engine designed to throw heavy missiles for breaching walls and bombarding targets during Siege warfare. It was widely used across the Middle Ages after originating in China and diffusing westward, ultimately becoming the most powerful pre-gunpowder artillery in Eurasia. Encyclopaedia Britannica; Scientific American.
Etymology and definition
The English word “trebuchet” derives from Old French trébuchet, related to trébucher “to overthrow; to stumble,” and appears in medieval Latin as trebuchetum; the term denotes a stone‑throwing engine. Merriam‑Webster; Etymonline. A trebuchet is defined by a long arm pivoting on a high axle with a sling at the long end and either a counterweight or a rope team at the short end. Encyclopaedia Britannica.
Origins and diffusion
Traction (man‑powered) trebuchets appear in Chinese sources between the 5th and 3rd centuries BCE and had spread to the Mediterranean by the 6th century CE. Encyclopaedia Britannica; Scientific American. From late antiquity into the early medieval period, traction machines replaced torsion artillery such as the onager in many regions due to simpler construction and safer operation. Scientific American.
Counterweight trebuchets emerged in the central and western Mediterranean by the 12th–13th centuries and rapidly transformed siegecraft with greater range and projectile mass. Dumbarton Oaks Papers—Chevedden; (book://Peter Purton|A History of the Late Medieval Siege 1200–1500|Boydell|2009). During the Mongol expansions, engineers from the Islamic world introduced counterweight machines—known in Chinese as huihui pao—to East Asia in the 13th century, notably at the sieges of Fancheng–Xiangyang (1273), accelerating their adoption in Yuan China and beyond. (book://Joseph Needham & Robin Yates|Science and Civilisation in China, Vol. 5, Part 6: Military Technology: Missiles and Sieges|Cambridge University Press|1994); Encyclopaedia Britannica.
Design and mechanics
All trebuchets exploit the mechanical advantage of a lever with a long projectile arm and short power arm; upon release, the short arm descends and the sling whips the payload into a high‑energy ballistic trajectory. Encyclopaedia Britannica. In counterweight versions, gravitational potential energy is stored by raising a massive weight (often stones, sand, or lead) attached to the short arm; in traction versions, teams pull ropes attached to that arm. Encyclopaedia Britannica; Scientific American.
Medieval engineers recognized and modern tests confirm that hinged (swinging) counterweights permit a near‑vertical drop, improving energy transfer compared with fixed counterweights. PBS NOVA; Scientific American. Numerical and experimental studies of trebuchet dynamics further detail the roles of the arm, counterweight, and sling in optimizing range. The Physics Teacher (AIP); arXiv.
Performance varied with scale and design. Estimates and records report large trebuchets hurling roughly 60‑kg projectiles to about 350 m, and some machines capable of casting stones of several hundred kilograms. Encyclopaedia Britannica. Contemporary reconstructions similarly demonstrate long ranges with heavy payloads when properly tuned. PBS NOVA.
Types and terminology
–Traction trebuchet (often called “mangonel” in some medieval Latin/vernacular sources): powered by coordinated pullers on ropes attached to the short arm; common before widespread counterweight adoption. Scientific American; (book://Peter Purton|A History of the Late Medieval Siege 1200–1500|Boydell|2009).
–Counterweight trebuchet: uses a fixed, hanging, or hinged mass; the hinged type generally showed superior range and efficiency. PBS NOVA; Scientific American.
Operational use
Trebuchets were used to batter curtain walls, topple merlons and towers, interdict works and gates, and deliver incendiaries or other munitions. Encyclopaedia Britannica. In the 13th century, the Mongol Empire fielded powerful counterweight engines—constructed and operated by Islamic engineers—during protracted sieges against the Song dynasty fortresses of Fancheng and Xiangyang, where long‑range, accurate fire played a decisive role. (book://Joseph Needham & Robin Yates|Science and Civilisation in China, Vol. 5, Part 6|Cambridge University Press|1994); Encyclopaedia Britannica.
In western Europe, a famous exemplar was “Warwolf,” assembled for Edward I at the siege of Stirling Castle in 1304; documentary and analytical studies indicate an immense timber structure capable of hurling very large stones, with modern estimates placing its overall height with arm extended at roughly 90 m. Guinness World Records; Journal of Medieval Military History (Boydell/Cambridge).
Although gunpowder artillery gradually eclipsed mechanical engines from the 15th century, trebuchets continued to appear where powder or guns were scarce; one of the last noted wartime uses was an attempted deployment by Hernán Cortés during the siege of Tenochtitlán in 1521. Encyclopaedia Britannica.
Munitions and special uses
Beyond stone shot, crews launched incendiaries, pots of combustible mixtures, and occasionally noxious or biological materials. Encyclopaedia Britannica. The often‑cited episode at the 1346 siege of Caffa describes plague‑stricken corpses hurled into the city; scholarly assessment deems such an attack plausible but debates its broader epidemiological significance. Emerging Infectious Diseases (CDC); Bulletin of the Atomic Scientists. The association of siege hurling and disease later became part of narratives about the spread of the Black Death, though modern studies caution against overgeneralization. Emerging Infectious Diseases (CDC); Bulletin of the Atomic Scientists.
Knowledge, science, and craft
Trebuchet building drew on practical carpentry, rigging, and empirical tuning of sling length, release angle, and counterweight mass. Scientific American. Historians have argued that observing hinged‑counterweight motion and lever mechanics informed medieval discussions of statics and positional gravity associated with Jordanus de Nemore; the machine also appears in broader histories of technology as a significant application of gravitational energy. Encyclopaedia Britannica; Dumbarton Oaks Papers—Chevedden.
Legacy and reconstruction
Modern experimental archaeology and educational engineering routinely reconstruct trebuchets, from small classroom kits to large outdoor engines, to study energy transfer, ballistics, and structural design. PBS NOVA; The Physics Teacher (AIP). Public displays and competitive events continue to demonstrate the trebuchet’s capabilities while offering insight into pre‑modern military engineering. Guinness World Records.
Scientific American; (book://Peter Purton|A History of the Late Medieval Siege 1200–1500|Boydell|2009).
PBS NOVA;