Onager Catapult – Roman Ingenuity at Work

Of all the catapult designs involved in this type of siege weapon’s ascent from simple machine to great demolisher of castle walls, the onager catapult perhaps has the best name.

Actually known as the mangonel, the onager catapult is a nickname for this machine of war. Since the mangonel had such a fierce kick, onager, which roughly means jackass, was incorporated as a pet name for the machine by those who used it.

From the ballista and the onager catapult to the creation of the great trebuchet, these machines greatly changed the face of warfare. Their impact on warfare is perhaps rivaled only by the introduction of gun power in the late middle ages. Machines such as the onager catapult enabled armies to attack from a distance with greater force than a bow could ever achieve. By allowing projectiles to be thrust at great distances, the onager catapult and its brothers in arms enabled armies to crush walls, strike fear and generally wreak havoc on the battlefield.

One of the many torsion type catapults created, the onager catapult was the Roman answer to earlier Greek machines. Like its predecessor, the onager catapult relied on torsion force for its projectile strength. The onager catapult, however, was constructed a bit differently.

The forerunner of the onager catapult, the ballista, is thought to have been introduced sometime in the 300s AD by engineers of Phillip of Macedonia. This model of catapult used two wooden arms, tightly wound ropes and a cord to assist in the hurling of deadly projectiles, such as spears, at an enemy. The ballista’s use of torsion force, just like the onager catapult’s, to launch objects earned it a lasting place in catapult history.

The onager catapult came along a bit later than the ballista. This model was similar in design to the Greek version, but called for only one wooden arm. The onager, however, had somewhat of a design flaw in that in called for a wooden barrier to be constructed. Its place in catapult history is nonetheless well documented as this model was still in use when the trebuchet arrived on the scene many years later.

Unlike its earlier Greek brother, the onager catapult is counted as a simpler design in catapult history. Despite this, it was quite effective at getting its job done, thus, explaining its continued popularity today among those who create replica and even full-size model recreations of these machines. Information on onager catapult making kits for simple desktop models and even full size replicas can readily be found on the Internet. These machines are very popular at reenactments and for class projects to display the principles behind catapults.


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