How Alexander the Great’s Army Evolved During His Conquests | History Hit

How Alexander the Great’s Army Evolved During His Conquests

Depiction of hypaspists, from 'History of Alexander the Great' (1913), edited.
Image Credit: Public Domain

Over the course of his conquests in Asia, Alexander the Great’s army underwent great changes to its warfare style and troop roster. New types of soldiers were embraced, while technological and tactical advancements were made as Alexander and his men battled a great variety of different adversaries in unfamiliar terrains.

One part of Alexander’s army that experienced great developments was his siege machinery, but the Macedonian infantry and cavalry would also evolve during Alexander’s reign. Upon his accession Alexander inherited the most revered infantry force of the time. Yet he would quickly make changes to it.

Alexander’s foot companions

Perhaps to ensure their loyalty, Alexander quickly extended the name pezhetairoi, or ‘foot-companions’ to include the entirety of his phalanx, while the elite infantry of Philip II became known as the hypaspists. Whether the pezhetairoi of Philip were the same soldiers who formed the hypaspists of Alexander is unknown.

From then on, the pezhetairoi of Alexander’s army experienced no significant changes for much of Alexander’s conquest. Its soldiers remained in basic units of 16 men, called a dekas, which could be combined to form a lochos of 128 men. 12 of these lochoi combined formed a battalion of 1,536 men.

Depiction of a Macedonian phalanx at the Battle of the Carts, from 1900.

Image Credit: Public Domain

The Hypaspists

Small changes in structure, however, do appear to have occurred for the hypaspists. New sub-commanders, appointed by merit, were introduced into the elite unit. Companies of 500 men were commanded by a pentakosiarch while units of 1,000 were commanded by a chiliarch. The hypaspists consisted of 3,000 men in total, so the unit had six pentakosiarchs and 3 chiliarchs altogether.

Later, following Alexander’s death, his hypaspists would receive a new name to reflect their high-quality: the argyraspides or ‘silver shields’ – used most notably by Eumenes during his great campaign against Antigonus.

Evolution of the ‘Pezhetairoi’

From the Granicus in 334 BC to the Hydaspes in 326 BC, the Macedonian phalanx was the nucleus of Alexander’s army. Yet as Alexander’s campaign went on reinforcements from Macedon ended and the number of his foot-companions slowly dwindled. Death, injury, old-age or having settled somewhere in his great empire – Alexander lost many of his Macedonians for these reasons. So much so that by 324 BC, less than 10,000 remained.

The mixed-phalanx

Struggling from this dearth of Macedonian manpower, Alexander had no option but to radically reorganise his Macedonian phalanx, incorporating Iranian infantry into the battalions. In each dekas, only four of the sixteen men remained Macedonians, stationed at the front and rear in the formation. The rest were Persian levies, not trained with the sarissa and instead using their native armaments: the bow and javelins.

This mixed phalanx lacked the cutting-edge and flexibility of its original, Macedonian counterpart. It thus did not stand the test of time following the death of Alexander. Alexander only intended his mixed phalanx of Iranians and Macedonians to be temporary until reinforcements from Macedon arrived. Yet the Macedonian king also knew he needed to bridge the divide between the conquered and the conquerors in his army if he were to be a legitimate King of Asia. One way he realised he could do this was by replacing his reliance on Macedonian infantry and improving the quality of his Asian footmen.

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The ‘Epigoni’

In 327 BC, upon his departure from Bactria, Alexander therefore ordered 30,000 picked Asian soldiers be recruited and trained in the Macedonian manner. They would undergo constant practice in the use of Macedonian arms and discipline for the next two years. At the beginning of 324 BC, they were presented to Alexander at Susa. Dressed in Macedonian attire and well-trained in the sarissa phalanx, Alexander labelled them his epigoni or ‘successors.’

By the end of 324 BC, Alexander’s powerful Macedonian sarissa phalanx was no longer the undisputed key infantry force in his army; now there was an equally prestigious formation. By creating such formidable regiments, Alexander had transformed the infantry significantly since the days of Philip.

Alexander’s Macedonian cavalry

The Macedonian cavalry also evolved during Alexander’s reign most notably with the Companions. Philip had arranged his Companions into ile squadrons based on the regions where they owned their land. Each squadron, 200 men-strong, was commanded by a squadron leader called an iliarch, who wielded great power in the field. Alexander altered this.

In 331 BC, perhaps to curb each squadron commander’s power, Alexander began to reform the command structure. He divided each ile into two smaller units called lochoi. In charge of each of these, he appointed new sub-commanders called lochagoi; the appointments were based on merit.

Depiction of the Companion Cavalry from Marshall Monroe Kirkman’s History of Alexander the Great (1913)

Image Credit: Public Domain

These sub-commanders thus owed their new-found power to Alexander – their loyalty became unquestionable. In such a move, Alexander significantly curbed the power of the original iliarch, as was the regional affiliation of each of the squadrons. Alexander would not stop reorganising his cavalry there. The following year, in 330 BC, Alexander made a crucial decision that would forever change the organisation of his Companions.

The Philotas affair

Philotas, the son of Alexander’s second in command, Parmenion and the overall commander of the entire Companion cavalry body, was accused of being involved in a conspiracy against the King and duly executed along with his father. Such an act had inevitable consequences for the organisation of the Companion cavalry.

Refusing to appoint a new commander of the entire cavalry body, Alexander now divided his Companions between two of his closest friends: Cleitus the Black, the commander of the Royal Squadron, and his closest friend, Hephaestion.


Furthermore, Alexander changed the name for the basic unit of the cavalry. From 330 BC onwards, he no longer labelled his Companion regiments as ile squadrons but hipparchies. The term ile continued to be used, but now only as a subdivision of each hipparchy – with two ile squadrons together forming one hipparchy.

As for the Royal Squadron, or Basilike Ile, this too appears to have had its name changed at this time to the agema. Consequently, Cleitus and Hephaestion also received a new title following Philotas’ execution to further affirm this reorganisation. They were called Hipparchs.

By 327 BC, Alexander had significantly increased the amount of Hipparchs commanding his companions to eight. From these Hipparchs would be some of the great names of Alexander’s campaign and the Diadochi – men such as Perdiccas, Craterus and Coenus.

Iranian cavalrymen

Alexander also introduced horsemen from the empire into his companion cavalry. By 324 BC, four hipparchies of the Companions consisted solely of picked Iranian cavalrymen. A fifth hipparchy that contained a mixture of oriental and Macedonian horsemen is also possible, while we know that certain Asian nobles were also incorporated into the Royal agema.

Consequently, the Companions were no longer a select Macedonian unit from the region’s nobility. Both among the hipparchies of the companions and with the creation of the epigoni, by the end of Alexander’s reign, certain new units had become as prestigious as the Macedonians.

The Prodromoi

Following 329 BC, any reference to the Macedonian light cavalry disappears completely from our sources. What happened to the prodromoi no-one can say for sure. Although many now suspect Alexander merged them with his reorganised Companions and placed them within the new-look hipparchies. From then on Alexander’s light cavalry came mostly from his Asian units – such as his horse archers from Dahae. By the end of Alexander’s reign, the Macedonian army had evolved significantly from the framework laid by his father Philip. 

Tags: Alexander the Great

Tristan Hughes