Roman Onager Shot

This stone onager shot is part of our Roman and Weaponry collection. The shot would have been used by a Roman siege engine called an onager, which was a type of catapult. It used the force of twisted rope to store energy for the shot.

It was called after an onager (wild ass) because of the kicking action of the machine.

The onager consisted of a large frame placed on the ground to whose front end a vertical frame of solid timber was rigidly fixed. A vertical spoke that passed through a rope bundle fastened to the frame had a sling attached which contained the projectile. To fire it, the spoke or arm was forced down, against the tension of twisted ropes or other springs, by a windlass, and then suddenly released. As the sling swung outwards, one end would release, as with a staff-sling, and the projectile would be hurled forward. The arm would then be caught by a padded beam or bed, when it could be winched back again.

The onagers of the Roman Empire were mainly used for besieging forts or settlements. They would often be armed with large stones that could be covered with a combustible substance and set alight. They could be outranged by bows.