The Sieges of Alexander the Great

by Stephen English

  Macedonian engineers evidently had been investigating the three materials that constituted the compound bow of the gastraphetes, namely sinew, wood and horn, and had come to the belief that, of the three, the sinew was the material that provided by far the greatest propulsive force. The principle of torsion came out of their desire to isolate and magnify this force in order to fire larger arrows or shot, and to do it over greater distances than achievable by a normal compound bow.

  The torsion principle was probably discovered, or at least developed into the standard two-arm device described above, in Macedonian at some point during the mid fourth century. The date is conventionally thought to be around 340 under the auspices of Philip II, although the first positive evidence for torsion springs date from between 338–326, during the reign of Alexander.24 We do know, however, that Alexander used stone-throwing catapults against Halicarnassus and probably Miletus in 334, and they would certainly have been torsion engines in order to provide the propulsive force necessary to do any damage at all to the walls. Given this, I believe the discovery of the principle of torsion can be narrowed down further to between 340–334; more than this cannot be claimed with any degree of certainty.

  Alexander’s stone-throwing catapults were of a rather different design than the ‘crossbow’ type of device, like the gastraphetes. Alexander’s single-armed stone-throwing catapults, called a mongakon, would have been similar in design, although perhaps less powerful, than the better known, but rather later, Roman onager. This was essentially a more traditional catapult design. Ammianus, a later Roman historian, described the Roman onager as follows:25

  The onager’s framework is made out of two beams from oak, which curve into humps. In the middle they have quite large holes in them, in which strong sinew ropes are stretched and twisted. A long arm is then inserted between the bundle of rope, at its end it has a pin and a pouch. It strikes on a huge buffer with a sack stuffed with fine chaff and secured by tight binding. When it comes to combat, a round stone (often clay balls with Greek fire in them, which explode on impact and burst into flames) is put in the pouch and the arm is winched down. Then, the master artilleryman strikes the pin with a hammer, and with a big blow, the stone is launched towards its target.

  The description is useful, as Alexander’s device would have been of similar design and operation, although, as noted above, would have been rather less advanced. The mongakon was essentially a mechanized staff sling; it consisted of a long shaft with a slingshot pouch at the end that was projected forwards by means of tension built up in rope at the fixed end of the staff.

  Alexander’s stone throwing devices represent a major shift in the balance of power during the conduct of siege operations. For the first time a besieging army could directly assault a city’s walls with a weapon far more powerful and devastating than a large arrow. The attackers now had the very real possibility of punching a hole through the defences of a besieged fortress, or of bringing down stretches of walls from a distance with the defenders being able to do very little about it other than hastily constructing a second layer of walls behind the section under attack, as the defenders did at Halicarnassus in 334. From this point forwards, the besieger would have the very real possibility of capturing any fortified position by force, rather than by attrition or deception. Alexander was to use this tactical shift brilliantly throughout his career. It was partly this development, and the success it helped Alexander achieve, that prompted Lane Fox to note that ‘it was as a stormer of cities that [Alexander] left his most vigorous impression’.26 Alexander may have been more famous as a field commander, but I hope to demonstrate during this book that he was a truly brilliant besieger of cities.

  Catapults were the terror weapons of their day; there is little doubt that they would have spread fear amongst those who were on the receiving end. To this end, they were not just used in sieges, but during field campaigns too, as demonstrated on two occasions during Alexander’s career. They did not have to be particularly effective against the opposition in terms of casualties to have a profound impact on their morale. In all of the many field campaigns that Alexander conducted, there are only two instances where he deployed artillery pieces against troops deployed in the open; both of which demonstrate very clearly their impact on the battlefield.

  The first incident occurred after Alexander had been compelled to temporarily abandon the siege of Pellium in 335, and was in the process of extricating his troops from the trap in which he had found himself, to a safer area beyond the Eordaicus River. Most of his troops managed to cross safely and gathered on the other side, but his rearguard, consisting of the Agrianians and some archers, had considerable difficulty in disengaging from the enemy that were pressing them hard. Arrian describes the situation:27

  He deployed his artillery on the bank of the river and ordered his men to shoot, at maximum range, all the types of missile that are hurled from machines. He also ordered the archers, who had already plunged in, to shoot from mid-stream. Glaucias’ men did not dare to advance within range. Meanwhile the Macedonians crossed the river safely, so that not one casualty was suffered in the withdrawal.

  Glaucias’ men did not dare advance within range of the catapult bolts, even though none of them were actually killed during the opening volley when they were in range. This psychological impact was clearly devastating and achieved exactly Alexander’s desired result of being able to disengage his troops and safely allow them to cross the river without being harried by the natives. This effect was almost certainly partly due to the catapult being a new form of weapon; it is highly likely that this was the first time the weapons had been seen by any of the inhabitants of that area of the Balkans.

  The second incident of Alexander’s employment of catapults during field operations also occurred in the context of a river crossing, this time offensively rather than to cover a withdrawal. At the crossing of the Jaxartes River in 329, a group of Scythians was occupying the far bank, making any attempt at crossing extremely hazardous, as the Macedonians would have been at a severe disadvantage against these excellent horsemen and horse archers. Arrian records the events that followed:28

  When all the skin floats were ready and the army in full equipment drawn up on the river bank, the catapults, at the word of command, opened up on the Scythians who were riding along the edge of the water on the further side. Some of them were hit; one was pierced through both shield and breastplate and fell dead from his horse. The Scythians were taken completely aback by the long range of the catapults, and that, together with the loss of a good man, induced them to withdraw a short distance from the river, whereupon Alexander, seeing their consternation, ordered the trumpets to sound and himself led the way over the water, followed by his men.

  Again, we can see that the actual impact of the catapult in a field operation was minimal, only one Scythian was killed, but the psychological impact of these weapons of apparently-limited destructive capability (outside of siege operations that is) was far greater than their operational effectiveness would warrant.

  These two examples (along with the Onomarchus incident) of the use of artillery in the field illustrate very well the limited theatre in which they could be employed effectively, but also the devastating impact that they could have, especially when employed against enemies who had not seen these weapons before. They had to be close enough to the enemy in order for their projectiles to reach; they also had to be on ground that was easily defensible, or did not require defending at all. These examples show very clearly the psychological effect of these weapons was out of all proportion to their actual physical effectiveness. On the two occasions when Alexander employed catapults in the field, only one man is recorded as being killed, and yet they helped in ensuring a successful outcome to both operations. Their true usefulness in field operations lay in their shock value, and in the confusion that they caused amongst the enemy, although this was exacerbated by the fact that on each occasion the enemy had never before seen such w
eapons. We can not be sure how effective they would be if used again, or against a more experienced or better prepared opponent. We can probably also argue that warriors such as the Scythians may well have been prepared to die in hand-to-hand combat; but they were evidently not so prepared to risk their lives when there was no possibility of striking back at the enemy.

  Catapults of the gastraphetes type were small, hand-held devices and could be easily transported from one siege to another. Once the principle of torsion was developed and catapults took on a rather larger structure, this became more problematic. They could no longer be carried by an individual and would have to be transported (and perhaps disassembled first) by cart or mule from place to place. The result of this was that they were likely to be designed to be dismantled while not in operation. This was partly for ease of transport and partly to ensure that the sinew was only under stress when the machine was in operation. This would prevent any reduction in the propulsive force provided by the sinew over time. The catapults, then, were in all likelihood ‘flat-packed’ for transportation over any distance and this is why we frequently hear of Alexander arriving at a city and having to wait for a period of time for the siege engines to catch up. This occurred at Tyre, Gaza and every siege after 332 in the northeast of the former Persian Empire, as well as in India. It would seem impossible for a fully-constructed catapult, or any of Alexander’s other siege engines (towers and rams, for example), to have been easily transported across desert, rivers or mountains like the Hindu Kush without first being dismantled. Scaling ladders could easily be built on site as a siege was about to begin, but better quality examples were probably also transported with the rest of the siege train. The ladders that collapsed at the city of the Mallians were probably hastily constructed and of rather poor quality.

  We hear frequently of Alexander’s famous siege train; for most of his career he required his army, or more likely flying columns detached from the main army, to move at considerably greater speeds than a mule and cart was capable of. This led, at almost every siege, to his arriving before his siege engines, which had to be brought up later. At Gaza, for example, there is a delay of several days as the engines were brought first by ship, and then dragged across the desert, from Tyre. Again, throughout the Indian campaign we see a similar situation where Alexander is usually delayed by a week or more waiting for his engines so he could begin the siege proper. In India this time was usually spent fortifying his camp and by constructing a double stockade around the fortification that he was besieging. This kind of circumvallation is not particularly common in Greek warfare, but became so during the Roman period, Julius Caesar being a particularly fine exponent of their use. See for example, his campaigns in Gaul.

  Whilst on site, catapults (as well as other siege engines) would also require moving. This would have been achieved by that application of manpower, or perhaps by being dragged by mules or other pack animals. They likely were not wheeled, which would have eased their movement, and so would have been assembled where they were required and only moved when absolutely necessary. It also evidently did not occur to the Greeks to mount their artillery pieces on a cart for easy transport and rapid deployment; this innovation did not occur until the Roman period.

  Rams and Ladders

  As noted earlier, the traditional and simplest piece of siege technology was the scaling ladder. These were simple constructions and would have been limited in size to the height of a sapling, as these would have formed the legs of the ladder, with the steps being fastened between them. They would only have been effective, therefore, against relatively low defensive walls. The rungs would also have been of wooden construction, lashed to the frame with twine or something similar. The construction materials did not lend themselves to supporting great weight either, and perhaps only one or two soldiers could climb them at any one time. When more troops tried to access the ladders, they would easily collapse under the excess weight, as occurred at the siege of the city of the Mallians after Alexander had leapt from the wall into the city with the intention of shaming and inspiring his men to follow after a particularly lacklustre beginning to the siege. The fact that we hear of no Macedonian deaths from this collapse suggest that the ladders were of no great size. We can estimate the height of ladders at that particular siege of perhaps only 3–4m, as we also are told that some troops stood on the shoulders of their comrades in order to gain the top of the city walls. Scaling ladders must have been of poor quality indeed if they were only 3–4m high and yet still collapsed under the weight of maybe five or six soldiers.

  Scaling ladders had two great advantages over other pieces of siege equipment in the ancient world, the first was that they were easy and quick to construct and did not, necessarily have to be carried from siege to siege as with catapults, siege towers and rams. The second great advantage was their flexibility and mobility of deployment. One of Alexander’s hallmark strategies, as I hope to demonstrate throughout this volume and its forthcoming companion The Field Campaigns of Alexander the Great, was his desire and ability to attack an enemy in more than one direction simultaneously. We see this with the many flanking attacks during his set-piece battles, but also during his siege operations. At Gaza, for example, he was concentrating his attention against one section of walls, but used ladders and catapults to attack at other points to prevent the defenders concentrating in the main sector. We see the same at Tyre where he used ship-borne artillery to attack all around the city in order to achieve the same effect. Scaling ladders made this tactic eminently possible during Alexander’s career as a besieger.

  Their ease of construction, tactical flexibility and rapidity of deployment made scaling ladders an integral part of almost all of Alexander’s sieges. Although they were seldom the primary means of victory, they did still have a role to play in the new world that Alexander had created for besieging armies. The very fact that they were used at almost every siege (with the exception of the mountain top sieges on the northeast frontier and some of the early Indian sieges) suggests strongly that defensive walls in the ancient world were almost exclusively small, otherwise ladders would not have reached the top.

  Another traditional siege device was the battering ram. It was not always possible to get over any given wall with ladders, or even with siege towers, and so the option of breaking through the wall was developed. The battering ram, as with the scaling ladder, was not a new creation of the great Macedonian engineers, but had been in existence for as long as there had been siege warfare. The simplest form of battering ram would have been a log carried by a number of men on either side that would have been used to pound a gate or doorway. It is unlikely that such a device would have had much impact against even the most primitive city walls and the force that a handful of men could impart would have been minimal, although enough to eventually break through a wooden door. This form of the weapon would also have been very exposed to missile fire from above as the defenders would have reacted to its presence. These early rams were relatively easily to counter by the defenders, and developments were fairly rapid.

  The next stage of development from this simple device would have been to suspend the ram, which likely would still have been a felled tree, from a wooden frame. This frame would then be pushed into position, the ram drawn back and released. Gravity would then take over and the ram would effectively drop towards the walls or gate of the fortress under attack. The force applied to the walls would be directly proportional to the distance the ram was drawn back and upwards (and to the weight of the ram). An alternative to this moveable frame would be for a fixed scaffolding framework to be constructed against the wall or gate from which the ram would again be suspended, exactly the same principle but a fixed device rather than a moveable one. This suspended ram design would represent a development in terms of the force able to be applied to the walls by the ram, but with either of these suspended ram options, the same problem would remain; missile fire from the defenders. The men involved in operating this
ram would be terribly exposed, and surely the construction crews charged with creating the scaffold if the device were fixed would have found it almost impossible to complete their work; attrition must have been very high for these men.

  By the mid fourth century, these defensive deficiencies in ram technology had been addressed. From this point, battering rams were transported within wheeled sheds to protect the operators from missile fire from above. These sheds would then be simply pushed into action against the wall or gateway as required. These mobile sheds could also double as moat-filling sheds to protect work parties, although this was never required by Alexander. This work would have been facilitated by the fact that the shed would have been a basic frame only, and it would have had no floor. This meant that filling in a moat was easy work, and also that the shed could be pushed from inside by the workmen while still being protected, and not from outside where they would have been vulnerable. This shed is an extremely simple device and would be proof against light missiles; large rocks would likely have gone straight through, especially if dropped from any great height. They would also have been vulnerable to fire arrows, and would likely have been covered with hides to reduce this risk.