The onager (British /'?n?d??/, /'?n???/, U.S. /'?n?d??r/) was a imperial-aera Roman torsion powered siege engine. The onager was first mentioned in 353 AD by Ammianus Marcellinus, who described onagers as the same as a scorpion.
Video Onager (weapon)
Etymology
It derived its name from the kicking action of the machine, similar to that of an onager (wild ass). This engine was sometimes called the mangonel, although that name may have also been used for a variety of siege engines.
Maps Onager (weapon)
Design
The onager consisted of a large frame placed on the ground to whose front end a vertical frame of solid timber was rigidly fixed. A vertical spoke that passed through a rope bundle fastened to the frame had a sling attached which contained a projectile. To fire it, the spoke or arm was forced down, against the tension of twisted ropes or other springs, by a windlass, and then suddenly released. As the sling swung outwards, one end would release, as with a staff-sling, and the projectile would be hurled forward. The arm would then be caught by a padded beam or bed, when it could be winched back again.
The scorpion, which is now-a-days called the wild ass, has the following form. Two posts of oak or holm-oak are hewn out and slightly bent, so that they seem to stand forth like humps. These are fastened together like a sawing-machine and bored through on both sides with fairly large holes. Between them, through the holes, strong ropes are bound, holding the machine together, so that it may not fly apart. From the middle of these ropes a wooden arm rises obliquely, pointed upward like the pole of a chariot, and is twined around with cords in such a way that it can be raised higher or depressed. To the top of this arm, iron hooks are fastened, from which hangs a sling of hemp or iron. In front of the arm is placed a great cushion of hair-cloth stuffed with fine chaff, bound on with strong cords, and placed on a heap of turf or a pile of sundried bricks; for a heavy machine of this kind, if placed upon a stone wall, shatters everything beneath it by its violent concussion, rather than by its weight. Then, when there is a battle, a round stone is placed in the sling and four young men on each side turn back the bar with which the ropes are connected and bend the pole almost flat. Then finally the gunner, standing above, strikes out the pole-bolt, which holds the fastenings of the whole work, with a strong hammer, thereupon the pole is set free, and flying forward with a swift stroke, and meeting the soft hair-cloth, hurls the stone, which will crush whatever it hits. And the machine is called tormentum as all the released tension is caused by twisting (torquetur); and scorpion, because it has an upraised sting; modern times have given it the new name onager, because when wild asses are pursued by hunters, by kicking they hurl back stones to a distance, either crushing the breasts of their pursuers, or breaking the bones of their skulls and shattering them.
The onagers of the Roman Empire were mainly used for besieging forts or settlements. They would often be armed with large stones that could be covered with a combustible substance and set alight. They could be outranged by bows.
History
The onager was used from the 4th century AD until the 6th century AD. In the late 6th century the Avars brought the Chinese traction trebuchet, otherwise known as the mangonel, to the Mediterranean, where it soon replaced the slower and more complex torsion powered engines.
See also
- Scorpion
- Ballista
- Springald
- Torsion siege engine
- Mangonel
- Trebuchet
References
Bibliography
- Purton, Peter (2009), A History of the Early Medieval Siege c.450-1200, The Boydell Press
Source of article : Wikipedia
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