Reconstruction of a polybolos, ancient Greek repeating ballista.

An Ancient Greek Machine Gun? The Innovative Catapult of Dionysius

The polybolos (which may be translated literally as ‘multiple thrower’) was a type of weapon used in the ancient world. The polybolos has been described as a sort of ballista / catapult that was capable of firing several projectiles before needing to be reloaded. That’s why it’s sometimes referred to as an ancient machine gun.

Polybolos: Improving on the Catapult

Whilst the catapult was likely to have been used since the 9th century BC (based on a relief from Nimrud), it was during the 4th century BC that the catapult began gaining popularity throughout the Mediterranean. In the Greek world, early catapults were large bows that relied on winches to draw the weapon back for firing. It may have been during the time of Philip II of Macedon (the father of Alexander the Great) that tight bundles of sinew / rope that functioned as ‘springs’ were used to replace the bow arms of the catapult. These catapults relied on torsion to fire their projectiles, and could either be used to fire arrows, like their predecessors, or be modified so that heavier projectiles, such as stones, could be hurled at enemy defences.  

Engraving of thirteenth-century catapult for throwing Greek fire. ( Public Domain )

The polybolos was a further improvement on the catapult technology that existed at that point of time. The polybolos is commonly believed to have been invented during the 3rd century BC by Dionysius of Alexandria, a Greek engineer who was working at the arsenal of Rhodes. During that time, the Rhodians had a particular interest in artillery, and were keeping abreast with the latest developments in this aspect of warfare. This was aided by their close relation with Ptolemaic Alexandria. It was at Rhodes that Philo of Byzantium, a Greek engineer and writer on mechanics, encountered and inspected a catapult made by Dionysius of Alexandria. This is recorded in Philo’s Belopoeica (a treatise on artillery), and our knowledge of the polybolos is derived from this piece of writing.

An automatic catapult, perhaps what a polybolos could have looked like.

An automatic catapult, perhaps what a polybolos could have looked like. (SBA73/ CC BY SA 3.0 )

Features of the Polybolos Catapult

Unlike the standard catapults / ballistae of the day, the polybolos could fire multiple projectiles before it needed to be reloaded. There were flat-linked chains on each side of the polybolos, which ran over pentagonal prisms at each end of the chain’s loop. It has been speculated that these prisms worked as inverted gears. By having a soldier turn the windlass attached to the rear prism, bolts could be locked, loaded and fired automatically. These projectiles were fed into the polybolos via a magazine that was attached to a rotating tray. This gave the polybolos a higher rate of fire than other ancient artillery pieces. For instance, a modern reconstruction of this weapon was found to have a firing rate of at least three times that of a standard scorpion (another artillery piece used by the Roman army). 

Parts of a polybolos.

Parts of a polybolos. ( Hellenica World )

Using the Polybolos Catapult to Attack

The polybolos was used mainly against enemy personnel, rather than against defensive structures such as walls or towers. One of the reasons contributing to this is the fact that the polybolos was able to lock on to a target. This, however, may also be a disadvantage of the weapon. An ancient writer is recorded to have complained that the polybolos was too accurate. The lack of dispersion in the shot pattern meant that using this piece of equipment to kill human units was an overkill.

A 19th century reconstruction of a polybolos by a German engineer by the name of Erwin Schramm, for example, was reported to have been so accurate that the second bolt fired from the weapon was able to hit its target, and in the process, split the first bolt.

Schramm’s reconstruction of a polybolos, in the Saalburg, Germany.

Schramm’s reconstruction of a polybolos, in the Saalburg, Germany. ( CC BY SA 2.0 )

Top image: Reconstruction of a polybolos, ancient Greek repeating ballista. Source: 3rdweal/imgur

By Wu Mingren


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