War has always been the catalyst for the rapid development of methods of warfare. Alexander the Great‘s conquests were no exception. Arguably the element of the Macedonian army that evolved the most during this period was his siege machinery. Just as his father had before him, Alexander quickly embraced the great potential of siege warfare for his campaign.
Alexander’s siege machinery
Ladders remained the most cost-effective way to capture a settlement and we know Alexander succeeded in taking many smaller towns with such equipment. Yet to conquer more formidable defences – dotted throughout Persia’s vast empire – Alexander required more complex, awe-inspiring engines.
Following in the footsteps of Philip and Polyidus, he was sure to further develop machinery throughout his reign – developments that would be key to some of his greatest military triumphs.
Just as Polyidus was for Philip, one engineer was more crucial than any other to the evolution of siege machinery during Alexander’s famous campaign. His name was Diades. A resident of Pella, Diades had been a student of Polyidus and succeeded him as chief engineer at the time of Alexander’s accession. It would be his siege developments that would be pivotal to some of Alexander’s greatest military feats.
Diades would create several new siege machines during Alexander’s reign. Arguably one of the greatest was the trupanon, the borer. Designed to ram down a settlement’s walls, simple borers had been in existence before Diades. Yet it was he who radically improved its design.
Like the ram, Diades’ borer consisted of a wooden beam with a metal head. It would be attached with ropes that were connected to pulleys and winches. So, when the mechanics pulled the ropes, it would exert a powerful force on the ram and cause a large breach in the wall. Diades not only increased the borer’s power, but also its protection. The beam was placed inside a mobile wooden shield called a Chelone, or ‘tortoise.’
Alongside the borer, Diades invented many other formidable siege engines. This included a grappling machine, designed for pulling down defences, and a much-improved drawbridge called an epibathra. This drawbridge acted as a gangway which soldiers could use to cross over from either a siege tower or ship. Although the drawbridge had been in use before Alexander’s time, it was Diades who dramatically increased its effectiveness.
Diades would also make modifications to many existing siege engines such as the ram (protected with a tortoise) and the siege tower (increased mobility and better drawbridge). Many of these engines would be used during Alexander’s successful Siege of Tyre – arguably Alexander’s greatest military feat. Consequently, Diades became known as the ‘man who took Tyre.’
Yet Diades was not the only innovative engineer that accompanied Alexander on his great conquest. Alongside other talented engineers such as Charias, they would create various siege machines, designed to counter specific defences. At Halicarnassus for example, we hear the Macedonians employed ditch-filling tortoises to aid an assault on the city.
Posidonius, another prominent member of Alexander’s engineering corps, would design his own modified siege tower for his patron. Its wheels were mounted on a sturdy timber chassis, which provided a strong base for the tower. Inside the chassis, 150 men would man the contraption that would push the engine’s wheels towards the enemy wall.
As well as containing other levels for stone throwing torsion catapults, or lithoboloi, the tower had two main floors. One floor was placed at a level that would be the same height as the opposing battlements. The other level was placed higher up, level with the top of a defending tower. Facing such a complex and deadly mobile machine must have been terrifying for any defending force.
Alongside these improvements to the siege engines, significant developments would also be made to Alexander’s artillery throughout his campaign. Polyidus’ creation of the torsion catapult under Philip was revolutionary for siege warfare and Diades and his fellow engineers continued to improve upon his initial design.
By the start of Alexander’s Persian conquest, no longer were these torsion catapults used to primarily fire arrows at the defenders themselves; thanks to further advancements they were now able to also fire stones with enough power to smash down enemy walls. They were called lithoboloi, or stone throwers.
Very quickly, Diades, Charias and the rest of the Macedonian engineers made further improvements to these lithoboloi. At the sieges of Halicarnassus and Tyre for example, we hear of highly-destructive torsion stone-throwers called petroboloi being used in Alexander’s army. These devastating machines could either be wheeled or wheel-less and could be placed on land, on siege towers and on ships.
Alongside the lithoboloi, Alexander continued to use other types of artillery such as the arrow-firing torsion catapult – the successor to the non-torsion oxybeles used by his father. Each of these machines, that Alexander used mainly to provide covering fire for his troops, were manned by teams of specialised artillerymen.
What made these great engines even more fascinating was their portability. Initially, it had been Philip and Polyidus who had started to design siege equipment that could be dismantled and re-used elsewhere. Yet it was Alexander who truly embraced this concept.
Throughout his campaign, both by sea and land, Alexander would have his great siege engines dismantled, transported and then reconstructed at various locations. During the siege of Gaza, for example, Alexander ordered Diades’ siege engines used at Tyre to be dismantled and transported by sea to him, where they were quickly reconstructed. Alexander’s siege equipment was thus formidable.