In 334 BC, Alexander III of Macedon crossed the Hellespont into Anatolia (modern-day Turkey) with a combined force of 54,000, launching a Pan-Hellenic counter-invasion of the Achaemenid Persian Empire. By 326 BC, within only eight years, his triumphant army had crossed the Hindu-Kush mountains and Indus River into Gandhara (modern-day Pakistan), having conquered the entirety of the Persian Empire without a single lost battle. Barely 30, Alexander had conquered more land than any individual in history to that point, founding an empire that spanned three continents and profoundly impacted the world for centuries to come. Of the many monarchs who have had the epithet of “the Great” bestowed on them in the millennia since, he stands as the greatest and most renowned.
Yet Alexander was standing on the shoulders of giants. He could not have achieved his conquests if not for the oft-overlooked accomplishments of his father, Philip II. Before his reign, Macedon had been peripheral in the Hellenistic world, crippled by a weak government and a lack of military or political power. Over 23 years, he transformed the kingdom into a powerful centralised state, with a professional standing army and a sophisticated administrative system, that unified all of Greece under its hegemony, laying the foundation for Alexander’s ‘greatness’.
Philip ascended to the throne in 359 BC in a time of national turmoil. Only a year before, the Macedonian army had been decimated by the Illyrians to the northwest, who were now preparing to invade Macedon itself. The kingdom also faced the ongoing threats of Paeonian raiders from Thrace as well as aggressive Athenian expansionism. All of this was exacerbated by a critical lack of resources and funding, as all of the major coastal cities along the Thermaic Gulf were under foreign control at this time, greatly restricting Macedonian access to sea trade, while decades of fighting had drained the treasury’s reserves.
Macedon’s political instability at this time also rendered it unable to resolve these problems. King Perdiccas III, Philip’s brother, had died fighting the Illyrians and was succeeded by his infant son, Amyntas IV. Philip, sensing the weakness of the Macedonian monarchy, seized the throne, but had to see off rival contenders Pausanias and Argeus, backed by the Thracians and Athenians respectively.
Despite the dire situation, once he came to power Philip was able to save Macedon from collapse through skilful diplomacy. He immediately opened talks with the Illyrians, paying tribute and conceding control of northern Macedonia in exchange for peace, even marrying the chieftain Bardylis’s daughter Audata to secure diplomatic relations, and paid off the Paeonian raiders with gifts for a similar agreement. At the same time, he bribed the Thracian prince Berisades to retract support for Pausanias and withdrew Macedonian troops from Amphipolis (a prosperous Athenian colony on the East Macedonian border) to appease the Athenians and end their support for Argeus, thereby ending the foreign meddling in the dynastic power struggle.
Once secure in his position, Philip used his diplomatic talent to advance Macedon’s interests abroad. This was most impressively done in gaining a foothold in Thessaly, a crucial region both because it was the gateway to mainland Greece and offered fertile land, soldiers and excellent horses for Macedon to exploit.
Instead of outright invasion, which would have turned Thessaly’s inhabitants against him, Philip supported the competing claims of local factions against each other as it suited him while guaranteeing their protection from the Phocians and Athenians. After many years of involvement in Thessalian politics, he invaded in 352 BC at the locals’ request to fight the Phocians; with his victory at the Battle of Crocus Field, he was appointed as archon (magistrate) of Thessaly for life, thereby taking control of the revenues of the Thessalian Confederation and of the united Thessalian army through cunning and guile.
The expansion of Macedon until Philip’s death continued, but now with renewed military and financial power behind it. Meanwhile, he adopted a soft power approach in mainland Greece from 346 to 343 BC by winning the friendship of politicians in the smaller city-states. Many Athenians in the war party, most notably Demosthenes, denounced this perceived Macedonian expansionism. Yet Philip continued trying to come to a peaceful accord with Athens.
It was only after 343 that Philip realised that Athens was beyond conciliation. For the next three years, he consolidated Macedonian dominance over Illyria and Thessaly, and from 342 to 340 BC began an invasion of Thrace that absorbed much of the region into Macedon. When Philip then moved to besiege the two Greek cities of Perinthos and Byzantion in 340 BC, perhaps because the former had refused to send aid to Macedon during the Thracian campaign, the war party in Athens, headed by Demosthenes, convinced the Assembly that this was a casus belli, resulting in the outbreak of war. This was because of Byzantion’s unique position on the Bosphorus Strait, through which Athens’s grain supply came.
The resultant Fourth Sacred War, in which Macedon fought Athens and Thebes, culminated in the Battle of Chaeronea in 338 BC. Though few details of the event remain, historians generally believe that the two sides were roughly equal in size, numbering around 30,000 infantry and 2,000 cavalry each. The battle was a decisive victory for the Macedonians, and even saw the 18-year-old Alexander lead the momentous cavalry charge against the famed Theban Sacred Band on the Greek right flank – an indicator of his future greatness in battle as a military commander.
After the Athenian and Theban forces were routed, no force now existed in Greece that could rival Philip’s war machine. Yet he laid siege to neither Thebes nor Athens, instead agreeing lenient peace terms to ensure their future cooperation in an invasion of Persia, and giving the Greek city-states some semblance of freedom and independence in his League of Corinth, founded in 337 BC to establish peace and mutual protection among its members. With all of the Greek city-states bar Sparta having joined the League, of which Philip had been appointed Hegemon, he had thus effectively unified Greece for the first time in history.
The success at Chaeronea, and indeed at all of the Macedonian conflicts during Philip’s reign, could be attributed to his crucial reforms of the Macedonian military, both in battle strategy and in equipment. Having seen the successes of other powers employing smaller and lighter equipment, he decided to reform his military on this model, sacrificing durability for mobility in all aspects of the Macedonian military operation.
However, before implementing new equipment and strategies, he needed a more professional army. Thus, his programme of reforms began with drilling the poorly-trained peasants that made up Macedon’s light infantry and recruiting 4,000 new levies, ensuring that they remained in constant training by decreeing that only the king could grant military discharge.
His innovations to the nature of Greek warfare followed shortly thereafter. Though he retained a smaller unit of traditional Greek hoplites, armed with heavy bronze armour and the hoplon shield, this was usually positioned at the rear of the Macedonian forces. Following Athenian innovations a generation earlier, he equipped the majority of his infantry with linen cuirasses to give greater mobility and smaller pelta shields that could be strapped to the arm, freeing both hands.
Furthermore, to increase focus and efficiency, he reduced the number of non-combatants following the army to one servant per ten soldiers and replaced all oxen with horses. The sudden increase in speed of the Macedonian war machine was instrumental in outmanoeuvring slower contemporary armies (such as in 357 BC, when the Illyrians were caught off-guard by the Macedonians’ sudden arrival and were unable to mount an effective defence), and was later a key factor in Alexander’s victories in Europe and Asia.
The most iconic military innovation under Philip was the development of the Macedonian sarissa, a 4-6 metre pike that allowed the Macedonian phalanx in close formation to be impenetrable from the front, creating a ‘wall of iron’ that had nearly two metres of extra reach over the spears used by opponents. Despite its obvious weakness in lacking manoeuvrability, in contrast to the nature of Philip’s general focus, it was extremely effective for its function: at the Battle of Chaeronea, the first recorded instance of its use, the sarissa phalanx was critical in pinning down the Athenian and Theban forces at the centre while other mobile troops attacked opposing flanks.
Yet the sarissa could hardly be said to be the weapon that won Macedon its empire. The greatest innovation of Philip’s reign was in fact in the Macedonian cavalry. Despite a prominent cavalry existing in Macedon long before Philip, many of the noblemen who had made up this force had perished with Perdiccas III in the battle against the Illyrians. Philip not only rebuilt the cavalry but also revolutionised its use.
A shorter form of the infantry sarissa, the xyston lance, was adopted by Philip’s cavalry, which provided greater reach without sacrificing mobility. Furthermore, inspired by Scythian and Thracian cavalry charges, Philip rearranged his cavalry formation into a wedge, where the squadron commander would lead at its tip and guide the direction of charge. The formation pierced gaps in the enemy positions with lightning speed; this was the first real deployment of cavalry as a shock unit in Antiquity, and served a crucial role in the ‘hammer and anvil’ tactic adopted by Philip, whereby the sarissa phalanx would pin the enemy’s infantry (the anvil) and the cavalry would wheel round and strike at their rear (the hammer). Thus, these developments all worked in concert with each other to form an extraordinarily effective whole.
In addition to these major innovations, Philip also incorporated elite units from allies and subjects all over mainland Greece and the Balkans to create an indomitable combined Macedonian fighting force. He incorporated javelin throwers from Paeonia and the best archers from Crete – a critical advantage at range, as other Greeks looked down on fighting with projectiles as cowardly. Indeed, he even made pivotal contributions to siege warfare, such as the development of the oxybeles (a mounted mechanical bow) and the torsion catapult by 340 BC. These were first used in the sieges of Amphipolis (357 BC) and Byzantion (340 BC).
Thus, the legacy of Philip II is of a great governor, reformer and military leader. However, his opportunity to expand on his achievements was lost due to his untimely assassination in 336 BC, aged only 46. The motives of the assassin, Philip’s bodyguard Pausanias of Orestis, is subject to significant historical debate. Whether Pausanias (as proposed by Cleitarchus and Diodorus) was a jealous lover of Philip, an enemy of Philip’s new father-in-law Attalus (according to Aristotle – the only contemporary account), or had been employed by Alexander, who had the most to gain from his death, the true motive remains uncertain. Regardless, the untimely death of the king led to the ascension of his son Alexander III to the throne, who would after two years launch his famed invasion of Persia.
Philip’s revolutionary military reforms undeniably set the groundwork for Alexander’s conquests in the Balkans and in Asia. The general infantry tactics remained largely unchanged for the entirety of Alexander’s conquests, demonstrating their enduring effectiveness not just against the Greeks but also the Persians and various other tribes of central Asia. At the Battle of Issus in 333 BC, despite being outnumbered two-to-one by the Persians, Alexander secured victory using Philip’s ‘hammer and anvil’ strategy. The same tactic was used at the Battle of Gaugamela in 331 BC, yet another against-the-odds Macedonian victory which effectively destroyed the Achaemenid Empire.
Alexander also greatly utilised Philip’s development of the army’s speed. This was demonstrated in his swift response to the Theban revolt of 335 BC, marching 300 kilometres in just three weeks to quash the rebellion. In Asia, despite his disastrous march through the Gedrosian Desert (modern Pakistan and Afghanistan) on his return from India, during which 20,000 men and animals died, the light equipment and speed of travel prevented an even greater catastrophe that might have proved terminal to his campaign.
There is no doubt that Alexander was a brilliant military commander. His daring and courage played no small part in rousing the troops, not least in cementing his image in history as a ‘Homeric’ leader yearning for glory on the battlefield – Plutarch notes that “Alexander was not only respected but loved by his soldiers,” and similarly Diodorus affirms that he “never hesitated to lead the attack in person.” His swift adoption of radically different strategies at different stages of the Asian campaign, such as the switch to guerrilla tactics when fighting the Aspasians in the mountains of modern-day Afghanistan, shows he was certainly a great commander independent of his father’s work – not that it is often doubted.
However, there is equally no denying that a conquest of such global proportions and magnitude could hardly have been possible if not for the groundwork laid by his father. When Alexander rose to the throne in 336 BC, he did not become the king of a backwater kingdom in northern Greece facing imminent foreign invasion and economic and military crises but of a Hellenic superpower that had already subdued the ever-quarrelling city-states of Greece. He possessed an economy, government and military machine poised and ready to conquer the known world. The conquest that made him Alexander the Great, though still extraordinary, was only made possible by King Philip II of Macedon.
Arrian, The Anabasis of Alexander.
Diodorus Siculus, Bibliotheca Historica.
Plutarch, Life of Alexander.
Polyaenus, Strategems in War.
Anson, E.M., 2010. “The Introduction of the ‘Sarisa’ in Ancient Macedonian Warfare.” Ancient Society, 40, 51–68. http://www.jstor.org/stable/44079933
Ashley, J.R., 2004. The Macedonian Empire: The Era of Warfare Under Philip II and Alexander the Great, 359-323 B.C. McFarland.
Cawkwell, G., 1978. Philip of Macedon. Faber & Faber.
Devine, A.M., 1975. “Grand Tactics at Gaugamela.” Phoenix, 29(4), 374–385. https://doi.org/10.2307/1087282
Errington, M., 2008, Macedon and the Hellenistic World. University of California Press.
Pomeroy, S.B, Burstein, S.M, et al., 2017. Ancient Greece: A Political, Social, and Cultural History. Oxford University Press.
Worthington, I., 2003. Alexander the Great: A Reader. Routledge.