The Traction Trebuchet: A Reconstruction of an Early Medieval Siege Engine

Abstract

The Traction Trehuchet: A Reconstruction of an Early Medieval Siege Engine W.T.S. TARVER Trebuchets are machine[s] invented by unbelieving devils. [Mardi al-Tarsusi, a.d. 1187] Traction trebuchets were medieval rotating-beam siege engines;1 they were powered by a human team pulling ropes and hurled stone projectiles from a sling. Traction trebuchets were entirely unlike ancient Greek and Roman torsion engines which used springs made of skeins of twisted sinew or hair, and they were quite unlike the later medieval trebuchets whose rotating beams were turned by large counterweights. Counterweight trebuchets were the dominant medieval siege artillery, but the survival of useful Roman-style torsion artillery into the Middle Ages is a myth with Renaissance origins. This myth, as well as confusion with counterweight machines, has hampered our understanding of traction trebuchets so much that some have even questioned their existence. I have reconstructed and tested a full-sized traction trebuchet in order to find out exactly how they worked and how they differed from other kinds of mechanical siege artillery. Why the Traction Trebuchet Fell into Obscurity The historiography of the traction trebuchet is inextricably linked to the contributions of centuries of antiquarians and scholars who have wrestled with difficult sources and baffling terminology.2 The Renais­ sance, enchanted with the recovery of ancient texts and knowledge, W. T. S. Tarver has an M.A. from the Institute for the History and Philosophy of Science and Technology at the University of Toronto and is a doctoral candidate in the Graduate Programme in History at York University. He wishes to thank the many people whose advice and critical comments have so greatly improved this article; those who volunteered to transport timbers and haul on ropes; and most of all, the few who fell into both camps, especially Bert S. Hall. 'Key terms are explained in the Appendix. 2Brian Stock puts it in a nutshell when he writes: “The Renaissance invented the Middle Ages in order to define itself; the Enlightenment perpetuated them in order to admire itself; and the Romantics revived them in order to escape from themselves” (Brian Stock, Listeningfor the Text: On the Uses of the Past [Baltimore, 1990], p. 69).© 1995 by the Society for the History of Technology. All rights reserved. 0040-165X/95/3601-0006$01.00 136 A Reconstruction of an Early Medieval Siege Engine 137 fostered the lingering notion that all things Roman were perfect. The Romans had siege engines; therefore the Romans had the best siege engines imaginable. The flourishing Renaissance mechanical tradition produced “theatres of machines” and similar works by authors such as Konrad Kyeser, Mariano Taccola, and Agostino Ramelli, including the celebrated sketches ofLeonardo da Vinci. These works first circulated in manuscript form and later achieved wide distribution through printing. They typically included drawings of fictitious machines which were later confused with real ones, greatly compounding the usual problems of distinguishing image from reality. Drawings of “ancient” siege engines, based on fragments of ancient descriptions fleshed out with artful ingenuity, usually conveyed mechanical cleverness and originality, rather than the details of any sort of living tradition.3 The Enlightenment inherited the twin ideas that the Romans had routinely employed devastating siege engines and that all medieval techniques were retrograde by definition. The popularity of the study of war as a suitable preoccupation for civilized gentlemen ensured that misapprehensions about siege machines became firmly rooted. Editions of authors such as Polybius4 were illustrated with engravings showing catapults and other devices based not on Greek or Roman primary sources but on the best (and often highly fanciful) guesses of the Renaissance. In the Romantic era, there was little difference between scholarly and popular interpretations of the Middle Ages? As Brian Stock put it, “To the Enlightenment, the Middle Ages were primarily a period[, but] for the Romantics, writing roughly a century later, they were also a state of mind.”6 The Middle Ages were seen as a time long before the English Civil War and the French Revolution, characterized by the stability, tranquillity, and obligation which were so much missed in the 19th century.7 This intellectual context informed 19th-century ’Conversely, Renaissance illustrations of counterweight trebuchets are...