Onager (weapon)

The onager (UK: /ˈɒnədʒə/, /ˈɒnəɡə/; US: /ˈɑːnədʒər/) was a Roman torsion-powered siege engine. It is commonly depicted as a catapult with a bowl, bucket, or sling at the end of its throwing arm. The onager was first mentioned in 353 AD by Ammianus Marcellinus, who described onagers as the same as a scorpion. The onager is often confused with the later mangonel, a "traction trebuchet" that replaced torsion powered siege engines in the 6th century AD.