Description
One of the simplest forms of one-armed catapult, the onager relied on twisted skeins of animal sinew which provided the power to hurl either rocks or shot. Inaccurate but powerful, it was an effective siege engine against buildings and fortifications, but was of far less use on the battlefield unless firing into massed infantry ranks. First mentioned by Philon of Byzantium in his treatise ‘Mechanics’, the onager had a sling-like cradle attached to a firing arm. This arm was inserted and twisted to propel its shot through torsion. As the firing arm was released, the sling-like cradle would unhook, firing the projectile. A padded beam was incorporated into the housing frame to restrain the arm. Larger machines could require as many as eight or ten crewmen, and the incredible recoil meant that they could not be easily or safely mounted on walls or towers. Quickly constructed wherever wood was readily available, onagers soon became a staple of ancient siege warfare.
