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Article by Peter Vemming Hansen 1994


The First Engines of War

Mechanical engines of war have existed since antiquity. The Romans developed huge engines of war with heavy ropes or cords, twisted for motive force, which could shoot ammunition such as stones or large arrows considerable distances.However, we do not know for certain when the first engines of war enter the scene of warfare. In A.D. 339 one chronicler states that Dionysos I, Tyrant of Syracuse, brought together engineers from all over the Mediterranean for the purpose of developing an engine of war powered by a large bow - requiring more power than one man could muster.It is not known what became of this project but it is to be feared that it ended up as almost any project supported by public funds - namely that the result compares well to the definition of a camel as being "a horse constructed by a committee"!As time passes we find more detailed descriptions of the old mechanical devices. They can roughly be divided into three groups - ballistas, catapults and trebuchets. The ballista was used with arrows while the two other types were designed for throwing ammunition such as heavy stones or other missiles.The ballista and the catapult are the oldest, while the trebuchet was developed only during the Middle Ages. All three types were in use well into the 16th century.The first weapons using gunpowder were introduced to the theatres of war in Europe during the 14th century but it took another 200 years before they replaced the old engines of war completely.The ballista and the catapult were spring-driven, either by tension, as when bending a bow, or by torsion where cords were twisted in a heavy timber frame. The trebuchet on the other hand uses the principle of counterpoise, whereby a heavy weight is attached to one end of a long beam and a pouch for the missile on the other. The beam is mounted on a solid stand or supporting frame.


Heavy artillery 

The trebuchets may rightly be named the heavy artillery of the Middle Ages. They were mainly siege machines and used for the purpose of hurling missiles over the walls of cities or castles. Trebuchets were used almost all over Europe, in great parts of the Mediterranean and in Asia.

It is believed that the first trebuchets were used in China as early as in the 7th century. From there this technology spread westwards and reached the Arab countries through Persia and Byzantium. The engines of war were in use all over the Mediterranean by the 9th century and the knowledge of these new and highly efficient weapons disseminated rapidly through the rest of Europe.

The first trebuchets - or the art of building trebuchets - arrived in the Nordic countries by way of Northern Germany, where engines of war are regularly mentioned in the books of the Hanseatic cities. There is some doubt as to the exact period in which these devices or knowledge of them reached Scandinavia.The Vikings may have known them at a very early stage, as the monk Abbo de St. Germain reports on the siege of Paris in his epic "De belle Parisiato" dated app. 890 A.D. that engines of war were used. Another source mentions that Nordic people or "the Norsemen" used engines of war at the siege of Angers as early as 873 A.D.

Throughout the Middle Ages and well into the 17th century, throwing devices dominate the theatres of war, but after a while the modern weapons - gunpowder cannons - become more efficient and the old types of weapons are abandoned. However, as late as 1575 scholars and military men could be heard discussing the virtues of the old engines of war in comparison with the new artillery, and even in 1779 throwing devices of antique design were utilised by an English general to fire at difficult targets in Gibraltar.


When the Cries Stop 

Trebuchets were fairly complicated engines, dependent on very heavy timber constructions for their proper functioning. The weight box might accommodate up to 20 tons of ballast consisting of stones, sand, or lead, and the pieces of ammunition might weigh as much as 300 kg. Various types of ammunition were used with the trebuchets. Stone shots have already been mentioned, but they also used beehives, small stones burned into clay balls which would explode on impact like grapeshot bullets, casks of tar and oil on fire, dead animals for introducing plagues and diseases, and finally prisoners of war and spies. It was said that one knew when they had landed - when the cries stopped!!

A fair number of medieval sources report the use of trebuchets. The Danish historian Saxo writes that King Erik Emune used trebuchets at the siege of Haraldsborg near Roskilde in the year of 1131. At this time the Danes had no knowledge of the finer arts of warfare and several Saxons were summoned to build and handle the engines.

The chronicler Olaus Magnus writes of another trebuchet used at Kalmar. An old woman happened to sit down on the sling pouch and by mistake triggered the trebuchet with her walking stick. As a result she was hurled through the air across the streets of the town, apparently without suffering any damage. Another story about trebuchets is told by Froissart in connection with the siege of Auberoche in 1334 by the French. In this case an English messenger was captured and sent flying back to the castle with his letters tied around his neck.

Apart from such incidents the trebuchet was generally considered a very reliable weapon and many cities or principalities had their own stock of dismantled trebuchets awaiting use in an engine store house. The "magister tormentorum" (master of trebuchets) was the official in charge of constructing, maintaining and handling the huge engines.


Various Types 

The early trebuchets operated on different principles compared to the later ones. All types, however, make use of the principle of leverage while the method of propulsion differs. The early engines were powered by hand. There was no heavy counterweight or ballast box but a number of people positioned behind the trebuchet were instructed to pull a rope and thus accelerating the throwing arm. Shortly after these early leverage engines became known in Europe, the Europeans rapidly developed the so called "Frankish trebuchet". In this engine manpower is replaced by a massive ballast box as counterpoise and force of propulsion, and the entire device is much more robust and heavier than the light, manpowered throwing machines. Within each category of trebuchets we see a wide range of varieties or hybrids of the basic principle of leverage and even engines combining the two methods of propulsion, manpower and counterpoise.

So far the scientists have only succeeded in defining a relatively small number of the many different types of trebuchets mentioned in the written sources. If we take a look at the words we know for trebuchets, there is an overwhelming multitude of different designations which makes it almost impossible to relate one name to a certain engine and difficult to find out whether these names are simply "nicknames" for a special type of trebuchet or if they define a certain category, such as biblia, biffa, lapidisca, machina, machinella, machinetum, manga, manganellus, maganum, mango, petratia, tormentur, trabucium, tripantum, and in Scandinavia blida, blide, machina, machinetum, manga, tormentum and valsslonva.

Arab sources recount more picturesque names for the manpowered trebuchets, for instance "the mother of hair on the head" or "the witch with ropes for hair". Even the larger engines powered by a heavy counterpoise seem to have been given special names. "Brigola" was the name of a heavy throwing machine whose ballast was divided into two parts, one on each side of the throwing arm. The translation means the "two-testicled engine". The "couillard" is the name of another type of trebuchet the ballast of which is not split, and this word simply means "testicle". It is evident that we are dealing with nicknames and military slang as other components of the huge trebuchets are also compared to parts of the human body, i.e. the struts supporting the throwing arm are called "thighs" or "hips".



Today a great number of replicas of medieval throwing machines can be found all over the world, but Middelaldercentret was the first museum to attempt reconstruction of one of these imposing engines of war in historic time and to perform a series of controlled tests ? well, since Napoleon III! Napoleon let his officers build a replica of a trebuchet on the basis of the notes of the medieval author, Marinus Sanutus, concerning the dimensions of the throwing arm. The reconstructed trebuchet was tested in the French town of Vincennes with cannon balls and shells as ammunition. The first 5 shots were fair tries, apart from the first one which was ?70 metres, which means that it fired backwards. After these 5 shots the engine broke down because the supporting structure was not solid enough. Even with these very modest results it is interesting to read in Captain Fave's report to the Ministry of War that the few shots fired had had remarkable directional stability.

1st shot: Cannon ball, 24 lbs: 175 m2nd shot: Shell, diameter: 22 cm, filled with sand: 145 m3rd shot: Shell, diameter: 27 cm, filled with sand: 120 m4th shot: Shell, diameter: 32 cm., filled with sand: 120 m

Middelaldercentret reported approximately identical test results more than one and a half a century later during tests of its replica trebuchet. Not only were the shots of high directional stability, but all in all the trebuchet delivered incredibly precise shots. Series of test shots during the trial could be placed within an area of 5 x 5 m at a distance of 160-180 m.Since Middelaldercentret built its first trebuchet it has launched almost 6000 shots and it has proved to be a most reliable weapon. This trebuchet is a high trajectory weapon which would have wrecked havoc on any besieged town or castle with incredible precision.By now Middelaldercentret has built and tested a great number of the various throwing machines of the Middle Ages, among them several large trebuchets. Each attempt at reconstruction has yielded further knowledge about the efficiency and use of these weapons as well as insight into the techniques of the siege. We now understand how and why defences are built, topographical solutions, and the enormous labour which poured into the defence against the engines of war and the eternal fight for improvement and further efficiency.Contrary to widespread opinion, siege was the prevailing form of war throughout the Middle Ages. The primary objective was to control and protect a territory (and of course use it) and this is the reason why centres of power were established ? everything from heavily fortified cities and huge castles to small fortresses and towers. These centres of power had to be protected, so war in those days mostly meant defending or attacking various types of fortifications. No wonder that mechanical engines of war dominated the history of war of that period.This development or arms race can be traced fairly accurately in a number of cases. From the sources we know that the most powerful of the early hand powered trebuchets could throw a stone of 90 kg a distance of about 120 m and this at a rate of one shot a minute or more. During the crusaders' siege of Lisbon in 1147, two hand operated trebuchets were in use, each of these powered by 100 men in shifts who managed to launch almost 500 stones in 10 hours. To some extent the rapid cadence of firing of the early trebuchets compensated for their lack of precision, and if we compare this weapon with other types of engines of war known at that time - the catapult and the ballista - the trebuchet was by far the most efficient and thus also the most used weapon (Chevedden 1996).In the first half of the 12th century the first counterpoise trebuchets appeared.  By then the hand operated engine had slowly developed into this fantastic weapon which could not only launch very heavy missiles but also worked with incredible precision over long distances. The new engine represented a revolution within siegecraft and its appearance led to the development of a wide range of new defensive measures in order to ensure protection against this frightening new weapon.


Trebuchets at Work 

Several sources describe the efficiency of trebuchets during sieges. Accounts of the Welsh Wars of Edward I in the late 13th century describe the use of trebuchets: "While Cornwall's English army pushed on with the siege of Dryslwyn .... an engine was constructed. Engineers and craftsmen were instructed to build the engine. The total cost of construction, purchases of hides, timber, and lead came to 14 pounds. Twenty quarrymen with four carts chiselled and transported the stone bullets to the trebuchet". The trebuchet was employed with great success during this siege. Later, on January 1st 1288, the same trebuchet was used for the siege on another fortress - Emlyn: "The engine which had done so much damage at Dryslwyn was transported by an escort 20 horses and 463 foot. Within five days it was hauled to Cardigan by way of St. Clears and Cilgeran. 40 oxen and 4 four-wheeled wains were being used. At Cardigan it was taken to the right bank of the Teify and repaired, and thence hauled by 60 oxen into the camp before Emlyn by January 10. The carting, with the hire and keep of the oxen, cost 45s. The wages of the blacksmith and costs of materials used in the repair, including 4s 6d paid for pig's fat for grease, came to 70s. Men were employed to pick up 480 stones on the beach below Cardigan and transport them by boat to Llechryd on the river and thence to carry them on 120 pack horses to the camp, thus earning 48s ... The total cost for the engine and siege work came to over 18 pounds. As not a single man was missing out of the paid portion of the army, it would seem that the surrender was peaceable, and probably the engine and the 480 great stones upset the tenacity of the defenders.

It is difficult to judge the value of money in those days, but if we look for comparisons we see that a mounted archer earned 6 pence a day working 7 days a week. His annual wages would be 9 pounds, 11 shilling and 6 pence. The yearly earnings of an infantryman was somewhat lower at 4 pounds, 11 shilling and 3 pence. Compared with a competent town craftsman the mounted archer would have earned almost three times as much.

The American historian Paul Chevedden has published a study of King James I (James the Conqueror), including a thorough presentation of the mechanical engines of war used during his many sieges. King James is said to have taken great interest in the artillery of the army, often supervised the setting up of the trebuchets for a siege, and even operated them himself. Among other things, Chevedden relates an event where the enemy had a stronger and more efficient engine than King James himself and by firing it continuously was able to keep the king at a distance. However, the sling pouch on the enemy's engine then coils itself around the throwing arm and quickly King James orders two light, hand powered trebuchets set up. When the operators fail their first shot, King James takes over and immediately hits the engine of the enemy with such force, that its counterweight box is destroyed and later on he even succeeds in breaking the throwing arm.


Other Engines of War 

As already mentioned we know of other types of leverage artillery from the Middle Ages but information about their employment and use is scarce. Engines powered by torsion are in widespread use during this entire period of history and are known in two versions: a one-armed and a two-armed engine. Both types originate more or less directly from the Romans who had developed such engines powered by torsion to perfection. Consequently, Roman sources are the most detailed ones on the construction and utilisation of these weapons.

One of the pioneers within the field of experimental archaeology was the German Major Schramm who built a number of impressively well made replicas of Roman torsion engines and carried out controlled tests of these reconstructions. Some of his reconstructed engines did not survive World War II but most of them can still be admired at the museum of Saalburg in Germany. It was on the basis of Major Schramm's work that Middelaldercentret attempted the reconstruction of a socalled mangonel, a one-armed torsion engine. The Romans named this engine an onager (wild ass) due to the curious movements of the engine when fired, where it lashes out like an ass. Because we followed Major Schramm's description of the building and testing of a mangonel - the medieval type - Middelaldercentret was spared repeating many of the difficulties which he had experienced at that time. For instance, he had great trouble with the construction of a throwing arm strong enough to withstand the tremendous force which is unleashed when the engine is fired, and it was only after many tests that he found a durable design. And even then, he was very careful when testing the onager. A completely different but equally dangerous detail suddenly revealed itself during the first launch. According to Schramm's design the movement of the throwing arm was to be arrested by means of a leather cushion, but on discharging the onager the throwing arm hit the cushion with so much force that the cushion nails flew like projectiles in all directions - a dangerous situation for the crew. The reason was that air was trapped within the leather cushion and Major Schramm should have used canvas as a cover to enable the air to escape through the fibres from within the cushion.

Bearing Major Schramm's experience in mind, Middelaldercentret constructed a mangonel or one-armed torsion engine. The engine was fitted with horsehair ropes as described in the Roman sources (even if women's hair is mentioned as the best) and the throwing arm was made of yew with a thickness of 15 cm. During a series of trial shots we succeeded in testing the engine to its limits and even though the shots were long and fairly precise they did not get close to the results seen with the counterpoise engines. This fits in well with the sources in which we read that even the largest torsion engines could only rarely fire shots of more than 130-150 m using projectiles of a maximum weight of app. 25 kg. Finally, the torsion engines were at a disadvantage under humid conditions because the cords were sensitive to humidity; they simply slackened.

There are only few descriptions of torsion engines in medieval manuscripts. A reason for this could be that these engines were not as popular as the trebuchets based on the principle of counterpoise, but they were employed in niches of warfare when they filled a part better than the new weapons, e.g. on board ships or under other special circumstances.

In addition to the torsion engines we know about engines of war powered by a large bow - by tension. Information about this type of weapon is again scarce even though a few clear illustrations still exist. From preserved crossbows we know about the construction of the strong bow which is an intricate laminate of tree and horn slats glued together and covered with a fabric. So far nobody has succeeded in reconstructing a bow of this kind, neither for a crossbow nor for the heavier catapults.


Trebuchets in Cyberspace 

Since Middelaldercentret built its first reconstruction of an engine of war, the trebuchet has rapidly conquered the world once again. Many people have become fascinated by the old engines of war and have built trebuchets of many different materials for many different purposes. Certainly the USA is in the forefront in this area, not surprisingly the idea is to be first with the biggest and to throw the heaviest object. Everything from Volkswagen cars to pianos are launched by trebuchets not to mention the annual competition with watermelons ...

The Internet is used extensively for exchange of information and experience: enthusiasts discuss details of construction and employment in chatrooms and on web sites. Those who have built a trebuchet or other artillery pieces see themselves as members of an international brotherhood and engage in lively exchange of intricate mathematics and formulae on the Internet. It seems as if people are more interested in the principle of the engines of war and not just the historical part. However, the impressive but transient quantities of information on the Internet here and there contain important observations and test results which do help us interpret the engines of war of the Middle Ages and their efficiency. American schools in particular have a strong preference for trebuchets and the like and many web sites demonstrate the results of such school projects.

Even though the trebuchet has experienced a renaissance as a leisure and school project theme in many countries, and more and more people show an interest in these fascinating old engines of war, we are still confronted with the huge task of interpreting and studying the medieval sources. It does not seem unrealistic to believe that in time we shall be able to describe, define and date a much greater number of the early weapons of this type - perhaps even more types than we know today - and the exciting reconstructive work may continue internationally on this foundation. As mentioned initially the study of these engines of war, their use and efficiency will remain one of the most important sources for an evaluation and understanding of the siege as warfare.



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Marsden, E.W. 1969/71: Greek and Roman Artillery. Historical Development and Technical Treaties. Oxford.

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Saxo: Danmarks riges Krønike, 1-3. København. 1970 (J. Olrik).

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