History of Roman artillery
Long before the Roman empire reached its peak, the ancient Greeks already used artillery. The Romans absorbed the knowledge and designs of Greek artillery and developed these further. In the hands of the Romans, the old Greek designs became quicker and easier in use and even more powerful. Throughout Roman history artillery was used in the field by legions and auxilia, as well as for the defence of cities and even on navy vessels.


The enemies of Rome, the ‘uncivilised barbarians’ took in turn the knowledge of artillery. Because of this, even after the fall of Western Roman empire, artillery was still a staple of medieval warfare. The designs did change over the centuries. The Roman ‘scorpio’ catapult became the ‘onager’ catapult in late Roman times and finally the medieval catapult with its characteristic fixed bowl.

In medieval times, the Roman names for artillery were still being used, but for other types of artillery then a Roman would have. Even between classic antiquity and late antiquity the names for artillery changed. For example while the latin word catapulta means shieldbreaker and was probably only used for small field artillery pieces such as the scorpio and not for big siege onagers, those onager type of machine is  what we now call a ‘catapult’.

The artillery of Pax Romana
Pax Romana makes use of a scorpio catapulta, a small lightweight ballista. Smaller pieces such as the scorpio catapulta would probably be used on the battlefield. While larger siege engines where more effective during a siege. A battery of scorpio’s could rapidly shoot bolts at enemy formations, shaking their morale. This would force them to loosen there formations and leave them vulnerable for a cavalry charge. While if the enemy tightens formations to repel a cavalry charge, they would be vulnerable to artillery barrages. Such interplay could be a good asset to the Romans on the battlefield. Small scorpio ballistae could also be placed on carts to make them a mobile weapon platform and capable to cross the often large battlefields.xv_scorpio3

How it works
Roman artillery is powered by torsion mechanics. This works by twisting a bundle of ropes to the point of great tension. On release the bundle of ropes would twist to its original position, the energy created by this is used to shoot or throw a projectile.

A scorpio catapulta, such as used by Pax Romana, could reach a maximum distance of 350 metres, with an effective range of 160 metres. The bolt projectile would reach a speed of 180 km/h. A force driven bolt could penetrate 1,5 mm iron plate, which is but a fraction of the damage dealt by lager Roman artillery pieces.
This type of weapon is often confused with the manuballista. A manuballista has the same design but is even lighter so it can be carried around and fired at the hip or shoulder. While the scorpio catapulta with its eight kg is too heavy to be used without its tripod.

The ballistarii (artillery soldiers) were not ordinary servicemen but immunes. This means that they got immunity for heavy labour and guard duty. This means that they got plenty of time to manufacture, maintain and practice with the artillery pieces. The balistarii and their engines were under the command of an optio ballistariorum. This officer commanded the artillery complement to an infantry formation or the artillery onboard a navy ship.  Like any officer, he made sure his men were trained and there equipment well maintained. Manning an artillery piece could take as little as one or two men for a scorpio while the giant siege ballistea could require ten to twelve men to fire.