Projectile Throwing Engines
Sir Ralph Payne-Gallwey
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The trebuchet always had a sling in which to place its missile.

The sling doubled the power of the engine and caused it to throw its projectile twice as far as it would have been able to do without it.

It was the length of the arm, when suitably weighted with its counterpoise, which combined with its sling gave power to the trebuchet. Its arm, when released, swung round with a long easy sweep and with nothing approaching the velocity of the much shorter arm of the catapult.

The weight of a projectile cast by a trebuchet was governed by the weight of its counterpoise. Provided the engine was of sufficient strength and could be manipulated, there was scarcely any limit to its power. Numerous references are to be found in medieval authors to the practice of throwing dead horses into a besieged town with a view to causing a pestilence therein, and there can be no doubt that trebuchets alone were employed for this purpose.

As a small horse weighs about 10 cwt., we can form some idea of the size of the rocks and balls of stone that trebuchets were capable of slinging. When we consider that a trebuchet was able to throw a horse over the walls of a town, we can credit the statement of Stella,1 who writes ' that the Genoese armament sent against Cyprus in 1376 had among other great engines one which cast stones of 12 cwt.'

Villard de Honnecourt2 describes a trebuchet that had a counterpoise of sand the frame of which was 12 ft. long, 8 ft. broad, and 12 ft. deep. That such machines were of vast size will readily be understood. For instance, twenty-four engines taken by Louis IX. at the evacuation of Damietta in 1249, afforded timber for stockading his entire camp.3 A trebuchet used at the capture of Acre by the Infidels in 1291, formed a load for a hundred carts.4 A great engine that cumbered the tower of St. Paul at Orleans and which was dismantled previous to the celebrated defense of the town against the English in 1428-9, furnished twenty-six cartloads of timber.5

All kinds of articles besides horses, men, stones and bombs were at times thrown from trebuchets. Vassaf6 records 'that when the garrison of Delhi

1 Stella flourished at the end of the fourteenth century and beginning of fifteenth. He wrote The Annals of Genoa from 1298-1409. Muratori includes the writing Stella in his great work, Rerum Italicarum Scriptores, 25 vols., 1723-38.

2 Villard de Honnecourt, an engineer of the thirteenth century. His album translated and edited by R. Willis, MA., 1859.

3 Jean, Sire de Joinville. He went with St. Louis to Damietta. His memoirs, written in 1309, published by F. Micheal, 1859.

4 Abulfeda, 1273-1331. Arab soldier and historian, wrote Annals of the Moslems. Published by Hafnire, 1789-94 Abulfeda was himself in charge of the hundred carts.

5 From an old history of the siege (in manuscript) found in the town hall of Orleans and printed by Saturnin Holot, a bookseller of that city, 1576.

6 Persian historian, wrote at end of thirteen and the beginning of fourteenth century. The preface to his history is dated 1288, and the history itself is carried down to 1312.



refused to open the gates to Ala'uddin Khilji in 1296, he loaded his engines with bags of gold and shot them into the fortress, a measure which put an end to the opposition.'

Figs. 18, 20., explain the construction and working of a trebuchet.


Fig.19- CASTING A DEAD HORSE INTO A BESIEGED TOWN BY MEANS OF A TREBUCHET From ' Il Codice Atlantico,' Leonardo da Vinci, 1445-1520


Fig. 20. -- THE ACTION OF THE TREBUCHET. A. The arm pulled down and secured by the slip-hook previous to unhooking the rope of the windlass. B. The arm released from the slip-hook and casting the stone out of its sling. C. The arm at the end of its upward sweep.

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