Archaeological excavations at Pompeii have focused primarily on the intense eruption of Mount Vesuvius during AD 79; However, new investigations have turned the spotlight on a violent chapter that occurred nearly 170 years ago.
Using advanced laser scanning and 3D digital imaging, lead researcher Adriana Rossi and the team discovered several unique and specific ballistic signatures on the walls of the city’s northern fortifications. According to research published in MDPI, the presence of these specific patterns suggests the use of polybolus (multi-shot or repeating catapults), which has been described as the equivalent of an ancient machine gun, in the Siege of Pompeii.
The polybolus represents a revolution in chain-launching from Hellenistic architecture and greatly advanced siege warfare in the Roman world.
Discovery of an ancient weapon, the “machine gun”, in Pompeii
Evidence of this ancient weapon, the “machine gun,” comes not from any physical parts, but from “ballistic scars” found on the limestone walls of Pompeii. The researchers found that the curved, tightly packed craters were much different from the large, discrete craters created by standard heavy catapults.
These impact marks were in the same arc-shaped groups, indicating that an object was fired from a fixed position and that recoil correction or hand-firing could cause a straight line of fire. It also appears that during the Social War period (89 BC), there was damage done by the Roman general Lucius Cornelius Sulla when he besieged Pompey, as mentioned in the paper “From Pompey to Rhodes, from Survey to Sources: The Use of Polybolus”.
General Sulla likely gained access to this technology through his campaigns in the eastern Mediterranean, and was thus able to defeat the Pompeian defenders.
Revolutionary mechanics of polypoulos
The Polybolos was an engineering masterpiece created in the 3rd century BC by Philo of Byzantium. This device differs from conventional projectiles in that instead of having to manually cock with each shot, it can reload and fire continuously until its magazine is exhausted.
It used a flat-link chain (considered the first known use of this type of mechanism in the world), which was attached to the winch.The polypoulos operator used a handle to rotate the lever, while at the same moment being able to pull the bowstring, drop another nail from the gravity-feed tray into the firing position and release the firing mechanism, all in one motion. Due to the design of the polypoles, a single battery of polypoles could provide effective suppression of defenders positioned on the city walls and clear a defensive position on a palisade with a rapid stream of projectiles.
How high-tech scans identified polypoulos
The research team used high-resolution LiDAR (Light Detection and Ranging) technology and digital photogrammetry in order to distinguish between types of artillery damage caused by natural corrosion. The researchers were able to measure the depth, diameter and path of each hole by creating a very dense 3D LiDAR point cloud on the wall’s surface. The polybolus effects were remarkably uniform, suggesting that they were triggered by the same (and thus mechanically consistent) machine rather than from different (and thus mechanically inconsistent) humans.
The pattern of artillery marks suggests to the research team that the polyballs were likely fired from high wooden towers designed to fire on Pompeian defenders. This may explain the concentration of groups of artillery traces at very high points of elevation along the northern fortifications.
