The Roman Onager catapult is a version of a Mangonel which uses a sling bucket to launch. The Onager was a powerful siege engine used by the Roman army during the late Roman Empire in battle and to lay siege to city walls and fortifications in their territories around the Mediterranean Sea and beyond. Its name comes from the Latin word for ‘wild ass’ – when it launched its payload it would have had a strong recoil kick resembling the native donkey of Persia (who knew?).