Chapter 3

Warrior: Alexander’s army

Alexander was engaged in military campaigning throughout his reign. Before he led his army against the Persian empire he had to deal with uprisings in the areas to the northeast and west of Macedonia, and then with the Greek city of Thebes, which he besieged and sacked. After crossing into Asia he fought three major pitched battles against the Persians, at the Granicus River (334), at Issus (333), and at Gaugamela (331), as well as one against the Indian king Porus on the Hydaspes River (326), and a number of smaller engagements. He successfully besieged a series of cities on the west coast of Anatolia and in the Levant. He was also faced with a long insurgency in Afghanistan (329–326), and more trouble in Pakistan during his march down the Indus Valley. He was, in the end, always successful. We have seen that the title of ‘undefeated’ became attached to him: it was well-deserved.

Many books have been written about Alexander’s generalship and his armed forces, illustrated with plans of his various battles. However, the evidence on which these accounts and plans are based is not easy to use, and there is much about Alexander’s achievements that remains guesswork. Even though Arrian himself had experience of military command, and wrote works on tactics, the ancient accounts of Alexander’s battles and sieges were less concerned with the details of military formations and command structures, and more interested in illustrating the less tangible aspects of warfare.


Some basic information about Alexander’s army can be taken as reliable. He crossed into Asia to begin his campaign with around 32,000 infantry and 5,000 cavalry. There he joined up with the force of around 10,000 that Philip had sent out two years earlier. Seven thousand of the infantry and 600 of the cavalry were from the Greek cities of the League of Corinth, a further 5,000 infantrymen were Greek mercenaries, and the rest were Macedonians and their allies. The Greek cities also contributed ships to Alexander’s fleet, but he was to disband this before the end of the year. As his campaign went on Alexander lost men to disease and to death and injury in battles and sieges, and through retirement, but he received a regular supply of reinforcements from Macedonia and Greece, and later on from within his newly conquered empire. Numbers provided by the ancient narratives for the size of his army remain generally consistent and believable throughout. The same cannot be said for the figures for the size of the armies he faced. At the battle of Gaugamela, for example, his second and final encounter with Darius III, figures for the Persian army range between 200,000 and 1,000,000 infantry and between 40,000 and 200,000 cavalry. Modern writers generally consider the likely number to have been below 100,000 men in total.

Alexander inherited his army from his father Philip, and its basic elements are referred to by enough ancient writers for us to understand its broad composition. The evidence from archaeology, in particular from grave goods, also helps our understanding of weapons and armour. There were cavalrymen armed with lances (but riding without stirrups, a fact which limited the impact with which they could charge); at the heart of the infantry was the so-called Macedonian phalanx, armed with 6-metre long pikes, called sarissas, and they are generally thought to have been flanked by men armed with thrusting spears and swords, and large round shields, like the hoplites of the Greek city states. As well as these there were light-armed troops, armed with javelins, bows, or slings. But attempts at greater specificity run into the problem that the ancient writers give a number of names for more specific units, without explaining what they are, and possibly sometimes using the same name for different units, or different names for the same units. The men of the phalanx are referred to as pezhetairoi (‘foot-companions’), but there are also references to asthetairoi: it is not certain what this word means. Similarly the hoplites may be called hypaspists (‘shield-bearers’), but towards the end of the campaign we have references to argyraspids (‘silver-shields’), who may be an elite group of these men or something different. Such uncertainties do not cause major problems in the reconstruction of battles, but they have generated a small scholarly industry of attempts to work out what the terms referred to.

Ancient armies were made up of more than their soldiers, and the presence of camp-followers is occasionally noted by the ancient writers. Every cavalryman would have had an attendant, and although Philip is supposed to have limited infantrymen to one servant for every ten soldiers, officers would have had more. As the campaign progressed, soldiers would acquire booty, and need slaves to look after it and them. There were also, no doubt, numerous other camp-followers offering their services, of many kinds, for food or pay. Periodically attempts were made to reduce the amount of baggage and the number of hangers-on, but as war-fighting was a recognized means of acquiring possessions much of the time the camp-followers must have outnumbered the soldiers.


Alexander’s forces also included a siege train. This was an aspect of warfare that Alexander appears to have developed considerably: catapults, battering rams, and siege towers, dismantled and loaded onto mule carts, would follow behind the army, along with the rest of the baggage train. The 7-month siege of Tyre (332) was one of his most celebrated achievements in antiquity. This is clear from the detailed accounts that we have of it, not only in the surviving historians, but also in the Alexander Romance, the popular version of Alexander’s life that circulated widely, and was continually embellished, in the ancient and medieval worlds. And it is one case where Alexander’s actions left a permanent mark on the landscape. The ancient city of Tyre was built on an island just off the Lebanese coast. During the siege Alexander built a causeway out towards the island, and although it was not completed, it led to the subsequent silting up of the channel in between, and so the ruins of ancient Tyre, such as they are, are now part of the mainland.


When it comes to reconstructing Alexander’s battles, the starting point is the accounts in the surviving sources. These can be supplemented by autopsy: modern writers have visited the sites of the battles—although ancient accounts of the topography are not always precise, and in some cases it has proved difficult to identify where encounters took place. For example, the ‘Persian Gates’, where an Achaemenid force tried to prevent Alexander getting through the Zagros Mountains to Pasargadae and Persepolis, has not been satisfactorily located. But even when we have several descriptions of a battle, and a good idea of where it was fought, there are severe problems facing any attempt at a detailed reconstruction. Ptolemy, the historian on whose work Arrian and Plutarch draw, probably took part in all the major battles of the campaign. And yet this would not necessarily make him a good source of information. From his position somewhere in the cavalry, he would only have seen a small part of the action, and most of this would have been confused and confusing. But in any case it is likely that Ptolemy did not rely primarily on his own memory for reconstructing events. He probably based his battle descriptions on those of Callisthenes, Alexander’s ‘official historian’, who may have witnessed the battles from a distance, and who would have been able to talk to a range of participants. But Callisthenes may not have been concerned with accuracy above all, as a consideration of the accounts of Alexander’s first battle against the Persians, at the Granicus River, will show.

The Battle of the Granicus

According to Arrian and Plutarch, Alexander marched from Troy, where he had visited the tomb of Achilles, and had taken from the temple of Athena a shield supposedly used in the Trojan War, to the River Granicus where he had found a Persian force commanded by the local satraps holding the far bank, which was high and steep. Parmenion, the senior member of his staff, suggested that Alexander should postpone his attack until the morning, but Alexander is said to have responded that the Hellespont would be ashamed if, after he had crossed it, he was now held up by the trickle that was the Granicus, and with that he led his troops into the river and against the Persians. Arrian gives rather more details about what happened next, but both authors include a list of Persians whom Alexander met and killed, one after another, once he had gained dry land on the far side. It has been recognized that this is the most difficult of Alexander’s battles to reconstruct, because the description is rather vague, and scholars have commented that the series of single combats fought by Alexander resembles passages from Homer’s Iliad more than anything else. The resemblance to Homer may in fact have been deliberate, especially if it is Callisthenes’ account that is being followed here. Early in the description of Achilles’ one day of fighting in the Iliad, Homer describes how the hero leaps into the river Scamander in pursuit of the Trojans, and battles with the river itself. Alexander claimed descent from Achilles, and Callisthenes’ description of the battle—first the leap into the river, and then the sequence of single-combats—will have been as much influenced by a wish to bring out the relationship between the two heroes as by any concern for accurate reportage. Diodorus gives a rather different account of the battle, in which Alexander camped overnight near the river and was then able to bring his troops over unopposed early in the morning, and fight on dry land. Whatever Diodorus’ source was, in this case his version may be nearer the truth.

If Diodorus was more accurate, then one of the elements in the other version that has to be rejected is the exchange between Alexander and Parmenion about the wisdom of launching an attack across the river. There are several such exchanges described between the two men in the surviving narratives, and they have a standard pattern: Parmenion offers sensible, if cautious, advice to Alexander; he ignores it, and turns out to be right to do so. Often, the exchanges are occasions for wit: when Darius sent a letter to Alexander offering peace terms, Parmenion is said to have remarked ‘I would accept, if I were you’, to which Alexander responded, ‘so would I, if I were you.’ There is no reason to assume, as some have done, that these stories reflect a growing rift between the two men. It is true that Alexander had Parmenion killed, after his son was convicted of plotting against the king, but up until that point Parmenion remained a trusted adviser, and was given rich rewards by Alexander. It is better to recognize that these are examples of a particular kind of story, that of the ‘wise adviser’. These stories depict an older man giving advice to a young ruler, so in Herodotus’ Histories the young Cyrus the Great is given advice by Croesus, former king of Lydia, and Xerxes is given advice by his uncle Artabanus, and by the former king of Sparta, Demeratus. Normally the young man, if he is wise, accepts the advice and prospers, or, if he is foolish, rejects it and suffers. But the stories involving Alexander reverse this pattern: he rejects the advice and still prospers, revealing that he is a truly exceptional ruler. The ancient writers use their narratives to illustrate their conception of Alexander’s character, sometimes at the expense of fidelity to the facts.

There were other ways of heightening the significance of Alexander’s achievements in battle. The narrative of Xerxes’ invasion of Greece, as told particularly by Herodotus, offered the historians of Alexander an opportunity to draw parallels between the two commanders. The clearest example of this is the description of Alexander’s entry into the province of Fars, where the city and palace of Persepolis was located, through a pass in the Zagros Mountains known as the Persian Gates.

The Persian Gates

As Xerxes marched through Greece towards Athens in 480, the only place where he could be stopped was a narrow passage between the mountains and the sea in central Greece called Thermopylae, a name meaning ‘Hot Gates’, so-called because of a local hot spring. Herodotus describes how the pass was defended by the Spartan king Leonidas and 300 Spartan hoplites, supported by some 5,000 other troops. According to his account the Spartans, who could have held out indefinitely, were betrayed by a local man called Ephialtes, who led a party of Xerxes’ troops along a little-known path that took them behind the Spartan position. On the third day of the battle, Leonidas found his troops surrounded, and he died on the battlefield. Xerxes’ victory left the path to Athens open, and he was able to sack the city not long after. Although the battle ended in an avoidable defeat—Leonidas knew about the path, but did not protect it adequately—it quickly came to be considered an example of heroic self-sacrifice, and this is how Herodotus, writing around 50 years later, describes it, and how it has entered popular culture. But the narrative could also be reused.

The historians all describe Alexander’s advance from Mesopotamia towards Fars through the Zagros Mountains, which involved going through a narrow pass referred to by Diodorus as the Susian Rocks, but by Arrian as the Persian Gates, held against him by a Persian commander, Ariobarzanes. Like Leonidas at the Hot Gates, Ariobarzanes had built a wall across the pass to protect his forces, but his forces were much greater, at 25,000 infantry according to Diodorus, and 40,000 according to Arrian—although as always these figures are unreliable and implausibly high. The authors describe how, after at first failing, like Xerxes, to break through the enemy position by a frontal attack, Alexander was told by a local man about a narrow path through the mountains that would bring him out behind the Persian lines. In the fighting that followed, the Persians were defeated, but unlike Leonidas, Ariobarzanes ran away. This was Alexander’s last military encounter on his way to Persepolis, which he destroyed (see Chapter 6) in revenge for Xerxes’ sack of Athens after Thermopylae. The similarities between the accounts of the battles at the Hot Gates and the Persian Gates are too great to be coincidental, and it is clear that whatever may have actually happened in the Zagros Mountains, it suited those who wrote about it to present it as an appropriate inversion of Xerxes’ sole victory in Greece.


Another important area where the concerns of ancient writers differ from those of their modern successors is in their attention to supernatural aspects of warfare. As a modern discipline, military history tends to focus on practical issues—the relative strength and quality of opposing forces, the nature of terrain, logistical organization, the competence of commanders and their subordinates. While the ancient accounts of Alexander’s campaigns are sometimes frustratingly lacking in these details, they are generally rich in accounts of omens and the advice of seers. This emphasis does reflect important truths about ancient warfare: given the uncertainty of war in general, ancient military commanders made considerable use of divination, looking to the gods to provide information that human resources could not. As a result, good manteis (seers), which means men who could not only correctly advise on the outcome of future actions, but who also had a record of being on the victorious side, were highly valued, and could expect rich rewards from the individuals and communities they served.In the surviving accounts of Alexander’s campaigns, above all in Arrian, his mantis, Aristander of Telmessus, plays a very visible role, interpreting a great variety of things, including the entrails of sacrificed animals, the behaviour of birds, dreams, astrological events like eclipses, and unusual phenomena such as sweating statues. All these are matters on which a seer would normally be consulted, but the stories need to be treated with care. It is a feature of ancient narratives, including historical ones, that prophecies always come true, one way or another. In Arrian and Plutarch, Aristander’s predictions, however unlikely, always turn out to be correct, and it is clear that once again their inclusion in the narrative serves mainly to make a point about Alexander. It is appropriate that the greatest general should be accompanied by the greatest seer, so Aristander’s perfect record of prediction is a reflection of Alexander’s own invincibility. Aristander is not present in accounts of Alexander’s last year, presumably because he had actually died at some point in the campaign, but it is only once Aristander has left the story that Alexander starts to witness omens foretelling his own death—not all of which are understood at the time.

The campaigns

Alexander’s expedition in Asia can be divided into two clear stages. In the first of these he was acting as the leader of an alliance of Greek states aiming to liberate the Greek cities of Asia from Achaemenid control, and to take revenge on the Persians for Xerxes’ invasion of Greece 150 years earlier. The first of these aims, the liberation of the Greek cities, was largely achieved in 334, the first year of the campaign, as Alexander marched south through Asia Minor before turning eastwards into central Anatolia. The Persians regained control of some of the cities that he had freed in the following year, but Alexander sent a force to deal with this, and by the end of 332, Persian power in the region was permanently ended. Revenge on the Persians ultimately took the form of the destruction of the city and palace of Persepolis in Fars. Alexander’s route there was by no means direct, but made sense militarily. In part it was determined by the actions of his opponent Darius in defending his territory. Alexander had disbanded much of his fleet not long after the start of the expedition, and needed to prevent Darius from using sea power. This was achieved by taking control of the major harbours along the east coast of the Mediterranean. The narratives of the Alexander historians offer additional explanations for Alexander’s campaign decisions, often in terms of Alexander’s personal desires: these may be accurate, but it is not clear what access they had to the workings of Alexander’s mind. The march down the Mediterranean coast brought Alexander to Egypt, and although entering Egypt led him away from Darius and from Fars, detaching the wealthy kingdom of Egypt from Darius’ empire would have made the detour well worthwhile. Once he left Egypt in the first part of 331, Alexander’s journey took him fairly directly over the Euphrates and Tigris, then down through Mesopotamia, by way of the royal capitals at Babylon and Susa, across the Zagros Mountains, and into Fars. Alexander entered Persepolis less than a year after leaving Egypt, and destroyed the palace a few months later. That this marked the end of the allied campaign is clear from Alexander’s next actions. He sent home the allied contingents, richly rewarding them, but he allowed any of the Greeks who wished it to re-enlist as mercenary soldiers. Therefore the army which set off from Persepolis in the summer of 330 was now concerned solely with fulfilling Alexander’s own aims.

The second part of the expedition took Alexander first in pursuit of Darius, whom he had already twice defeated. When Darius was assassinated on the orders of one of his subordinates, Bessus, he became Alexander’s new target. The pursuit led Alexander into Bactria and Sogdiana, the northeastern corner of the empire, where the local elite were slow to accept the change of regime. Hence it took three years for Alexander to settle the region. Alexander’s next move, southeast into the Punjab and the Indus Valley, is best seen as a new campaign. How many of the troops that had crossed the Hellespont with Alexander in Spring of 334 were still with him eight years later we cannot tell: injured and aging soldiers will have been sent home to be replaced with reinforcements sent from Macedonia throughout this period. Most of the older officers had also either died or been left in positions further west, but Alexander’s younger companions remained with him. The Indian campaign brought Alexander downriver to the Indus Delta and his first contact with a tidal ocean. The last phase of the journey was back through southern Iran to Fars, with a fleet also being sent up the Persian Gulf towards southern Mesopotamia. Alexander then spent the last 18 months of his life in what is now western Iran and eastern Iraq.

The rest of this book will not provide a detailed narrative of the expedition. Although the following chapters are organized roughly chronologically, they are more thematic, and make use of contemporary material to show how Alexander fitted into the world through which he travelled. The simplest way to follow Alexander’s campaign is by using the map and the timeline provided at the front of this book.

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