Onager (weapon)

[2][3] According to two authors of the later Roman Empire who wrote on military affairs, the onager's name, meaning wild ass,[4] derived from the kicking action of the machine that threw stones into the air.

A vertical spoke that passed through a rope bundle fastened to the frame had a cup, bucket, or sling attached which contained a projectile.

This time, inside a wooden frame that had to be of massive proportions, a single arm was held in a twisted skein of sinew or horsehair.

[22] The late-fourth century author Ammianus Marcellinus describes 'onager' as a neologism for scorpions and relates various incidents in which the engines fire both rocks and arrow-shaped missiles.

Originally it used a bucket or cup to hold the projectile but at some point it was replaced with a sling, which elongated the throwing arm without burdening it and allowed for a greater range of shot.

[26]In the late 6th century the Pannonian 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.

Swiss general Guillaume Henri Dufour made another attempt to reconstruct the onager based on the work of de Folard in 1840.

Later, the German major-general Erwin Schramm and the British scholar Eric Marsden made a reconstruction of the onager[31] which became the basis of the modern understanding of the weapon.

One reason the onager may have become the Roman military's primary type of torsion catapult was because it was easier to produce and required less technical knowledge to operate.

[34][35][36] Ammianus Marcellinus described an instance during an Alemanni incursion in Gaul where although the onager fired a rock that did not kill anyone, it created mass confusion amongst the enemy and routed them.