Under the reign of Philip II (359–336 BC), the Argead kingdom of Macedonia, initially at the periphery of classical Greek affairs, came to dominate Ancient Greece in the span of less than 25 years, largely thanks to the character and policies of its king. In addition to utilising effective diplomacy and marriage alliances to achieve his political aims, Philip II was responsible for reforming the ancient Macedonian army into an effective fighting force. The Macedonian phalanx became the hallmark of the Macedonian army during his reign, combined with Companion cavalry, hypaspists and light infantry. His army and engineers also made extensive use of siege engines. Chief among Philip's Thracian enemies was the ruler Kersebleptes, who may have coordinated a temporary alliance with Athens. In a series of campaigns stretching from 356 to 340 BC, Philip II managed to ultimately subjugate Kersebleptes as a tributary vassal, conquering much of Thrace in the process. Philip II also fought against the Illyrian king Bardylis, who threatened Macedonia proper, and against Grabos II and Pleuratus in Illyria (centred in modern-day Albania). In his newly conquered territories, he founded new cities such as Philippi (modern Filippoi, Greece), Philippopolis (modern Plovdiv, Bulgaria), Herakleia Sintike (modern Rupite, Bulgaria), and Herakleia Lynkestis (modern Bitola, North Macedonia).
Philip II eventually campaigned against the city-state of Athens and her allies in the Aegean region, as well as Thebes after the decline of its hegemony in mainland Greece. In the defence of the Amphictyonic League of Delphi and in conjunction with the Thessalian League, Macedonia became a key player in the Third Sacred War (356–346 BC), defeating the Phocians, commanded by Onomarchus, at the Battle of Crocus Field in 352 BC. While poised to launch a direct assault on Athens in 346 BC, the Macedonian king was met with an Athenian embassy that arranged the Peace of Philocrates. As a result, Macedonia and Athens became allies, yet Athens was forced to relinquish its claims to the city of Amphipolis (in modern-day Central Macedonia).
The Peace of Philocrates eventually broke down as hostilities reignited between Athens and Macedonia. Demosthenes, an Athenian statesman who was partially responsible for engineering the peace treaty, delivered a series of speeches encouraging his fellow Athenians to oppose Philip II. The Macedonian hegemony over Greece was secured by their victory over a Greek coalition army led by Athens and Thebes, at the Battle of Chaeronea in 338 BC. In the aftermath the federation of Greek states known as the League of Corinth was established, which brought these former Greek adversaries and others into a formal alliance with Macedonia. The League of Corinth elected Philip as strategos (i.e. commander-in-chief) for a planned invasion of the Achaemenid Empire of Persia. However, Philip was assassinated by his bodyguard Pausanias of Orestis before he could begin the campaign, a task that instead fell to his son and successor, Alexander the Great.
Background
Greece in the early 4th century BC
In the aftermath of the Peloponnesian War, the militaristic city-state of Sparta had been able to impose a hegemony over the heartland of Classical Greece (the Peloponessus and mainland Greece south of Thessaly), the states of this area having been severely weakened by the war. This state of affairs was resented by many of the Greek city-states, which had traditionally been ferociously independent, and led directly to the Corinthian War of 395–387 BC. Sparta emerged from this conflict with its hegemony intact, though only as a result of Persian intervention, which led to the so-called King's Peace. The fragility of Spartan dominance had been demonstrated however, and in the next decade, the Thebans would revolt against Sparta. The Spartans were unable to successfully quell the revolt, leading to de facto Theban independence. Then, after several years of desultory conflict, the Thebans finally met the Spartans in open battle at Leuctra (371 BC), and under the leadership of Epaminondas inflicted an unprecedented defeat on the Spartan army, killing the Spartan king Cleombrotus I in the process.
Following up on this victory, Epaminondas invaded Peloponnesus in 370 BC and began dismantling the basis of Spartan dominance. Spartan power rested on the forced labour of the helots of Messenia, which allowed the entire male Spartan population to dedicate themselves to warfare. This focused military training system had previously enabled Sparta to exert power out of proportion to its small population. However, after their losses at Leuctra, the Spartans were unable to resist Epaminondas's invasion, and he marched into Messenia and liberated the helots, thereby permanently crippling Sparta. The Thebans then began to extend their influence over Greece, effectively replacing the Spartan hegemony with their own. The Theban generals Pelopidas and Epaminondas campaigned all over Greece for the next 9 years to further Theban power and influence. In 362 BC, Epaminondas's fourth invasion of the Peloponnesus, which reached its climax at the Battle of Mantinea, brought almost every state in Greece into the conflict, on one side or the other. Although the Thebans and their allies were victorious at Mantinea, Epaminondas was killed, and Theban losses were heavy. Xenophon, summing up his account of Mantinea, suggests that:
When these things had taken place, the opposite of what all men believed would happen was brought to pass. For since well-nigh all the people of Greece had come together and formed themselves in opposing lines, there was no one who did not suppose that if a battle were fought, those who proved victorious would be the rulers and those who were defeated would be their subjects; but the deity so ordered ... that while each party claimed to be victorious, neither was found to be any better off ... but [that] there was even more confusion and disorder in Greece after the battle than before.
The years of conflict which resulted from the Theban attempts to reorganise Greece had left much of the country war-weary and exhausted; a general peace (excluding only a recalcitrant Sparta) was therefore concluded between all the states of Greece in the aftermath of Mantinea. With the death of Epaminondas and significant loss of manpower at Mantinea, the Thebans returned to their more traditional defensive policy, and within a few years, Athens had replaced them at the pinnacle of the Greek political system, and Theban influence faded quickly in the rest of Greece. It was the Athenians, and their second League, who would be Macedon's main rivals for control of the lands of the north Aegean, and a major theme during the period was the regular state of war between Macedon and Athens.
Philip's accession
In 360 BC, the Macedonian army under Perdiccas III had been defeated in battle by the Illyrians; Perdiccas and 4,000 troops had been killed. The Illyrians prepared to invade Macedon; meanwhile, the Paionians were ravaging Macedonian territory, the Thracians were preparing to invade in support of the pretender Pausanias, as were the Athenians, in support of a different pretender, Argeus. In short, Macedon was in another of its periodic crises.
The nominal heir of Perdiccas, his son Amyntas IV, was at this time still an infant. Philip, the oldest surviving son of Amyntas III, was the obvious candidate to rule Macedon and was acclaimed by the army, probably as king. It is also possible that he was initially acclaimed as regent for his nephew Amyntas IV, and later usurped the throne, although if so, he did not harm Amyntas. Either way, Philip II became king by 359 BC, and began energetically attempting to save Macedon from destruction.
Macedonian recovery (359–358 BC)
Reconstruction of the army
Philip's first priorities were to reconstruct the Macedonian army, and restore the morale of both the army and the people. He held a series of assemblies with the Macedonian people, and "exhorting them with eloquent speeches to be men, he built up their morale". He exhaustively re-trained his men with new tactics and equipment. In particular, he instigated the use of the phalanx formation by the Macedonian foot-soldiery, and equipped the troops with 6-metre long pikes (the sarissa), in contrast to the 2–3-metre spear (doru) used by Greek hoplites.
Diplomacy
At the same time, Philip engaged in a flurry of diplomatic activity. He bribed Berisades, son of the Thracian king Cotys, to withdraw Thracian support for Pausanias, and thereby prevented the Thracian invasion. Similarly, he bought off the Paionians with gifts in exchange for their withdrawal from Macedon. Philip may also have concluded a treaty with the victorious Illyrian king Bardylis, possibly surrendering large parts of Macedon in exchange for peace. Although no evidence remains of such a treaty, the fact that Illyrians did not follow up their victory despite Macedon's weakness is suggestive that some agreement was reached. Philip also married Bardylis's daughter (or niece), which may have formed part of the treaty. At any rate, Philip's diplomacy gave Macedon some breathing space and time for recovery.
Battle of Methone
Philip realized that the sole intention of the Athenian support for Argeus was to recover Amphipolis (see below), which they hoped to do by placing Argeus on the throne. Philip therefore withdrew the Macedonian garrison from Amphipolis and declared it autonomous, to undermine the purpose of Athenian support for Argeus.
The Athenian expedition, led by Mantias, still landed at Methone on the Macedonian coast, with 3,000 mercenary troops. Mantias now declined to leave Methone, so Argeus instead led the troops to the ancient Macedonian capital of Aegae, hoping that the populace would declare him king. However, the people of Aegae showed no interest in doing so, and Argeus therefore marched back to Methone. On the way, he was attacked and defeated in battle by Philip, many of the Athenian mercenaries being slain and the rest taken captive. According to Diodorus, this victory did much to restore the morale of the Macedonian army, and gave the soldiers encouragement for the battles to come.
Having defeated the last immediate threat to Macedon, Philip returned to diplomacy. He released the Athenian prisoners immediately, and sent ambassadors to Athens. He was prepared to abandon all claim to Amphipolis, and this, coupled with his treatment of the Athenian prisoners, persuaded the Athenians to make peace with him.
Paionia and Illyria
The following year (358 BC), Philip heard that the Paionian king, Agis, had died. Taking advantage of their political disarray and transition of power, Philip marched his army into Paionia, where he defeated the Paionians. He then compelled the tribe to swear allegiance to Macedon.
Philip was now able to turn to the Illyrians, who were still occupying much of upper Macedon (whether agreed by treaty or not). Elimea and Eordaea had probably been the only principalities loyal to the Macedonian kingdom during the Illyrian invasion. On the other hand, Lynkestis was ruled by a competing dynasty related the Macedonian throne (and probably to Philip's mother, Eurydice) and other Upper Macedonia districts had links to foreign powers. Pelagonia was a traditional Athenian ally in Upper Macedonia whilst Lynkestis, Orestis and Tymphaea had links with the Molossian kingdom and Epirus. All of them enjoyed under the Illyrian and Paionian threat an opportunity to defy the central power and many were now under Bardylis hegemony.
Philip held an assembly of the army, gathered together a force of 10,000 men and 600 cavalry and marched into Illyria. Philip had also married Phila of Elimeia, ensuring an alliance with a principality of Upper Macedonia reputed by their cavalry. Bardylis, hearing of the preparations, sent ambassadors to Philip, proposing peace on the basis of the status quo. Philip rejected this, insisting that the Illyrians must withdraw completely from Macedonia, so Bardylis instead prepared for battle, raising 10,000 men and 500 cavalry, according to Diodorus.
Diodorus preserves the only account of the battle, which Beloch suggested may have taken place near Monastir. He says that:
When the armies approached each other and with a great outcry clashed in the battle, Philip, commanding the right wing, which consisted of the flower of the Macedonians serving under him, ordered his cavalry to ride past the ranks of the barbarians and attack them on the flank, while he himself falling on the enemy in a frontal assault began a bitter combat. But the Illyrians, forming themselves into a square, courageously entered the fray. And at first for a long while the battle was evenly poised because of the exceeding gallantry displayed on both sides, and as many were slain and still more wounded, the fortune of battle vacillated first one way then the other, being constantly swayed by the valorous deeds of the combatants; but later as the horsemen pressed on from the flank and rear and Philip with the flower of his troops fought with true heroism, the mass of the Illyrians was compelled to take hastily to flight.
According to Diodorus, some 7,000 Illyrians died in the battle. The Illyrians withdrew from Macedon and sued for peace. After this campaign Philip had established his authority inland as far as Lake Ohrid. Not only were the Illyrians expelled, but also the king Menelaus of Pelagonia was exiled to Athens, leaving Philip as the sole overlord of the Upper Macedonia area. This allowed him to levy troops from a wider manpower pool during the rest of his reign. Some areas like Pelagonia were outright annexed whilst others like the loyal Elimea or the more distant valleys kept their autonomy as vassals. Philip reorganized the Macedonian administration into districts or ethne and established the companion system to keep the Macedonian nobility controlled. Under that scheme, the sons of the Macedonian nobility were included in the king's household rather than autonomous lords. Many of Philip's and Alexander's more famous generals in the years to come were from the Upper Macedonia nobility.
Philip also gained the favour of the Epirotes, his southwestern neighbors, who had also been at war with the Illyrians. The following year, Philip married the niece of the Molossian king of Epirus, Myrtale, which may have brought the frontier area between Macedon and Epirus, Orestis, under Philip's sphere of influence as part of her dowry.
To the northwest, Illyrians tribes like the Taulantii or the Dardanians had been expelled but not subjugated. To the north, the Strymon or the Nestus were the limits of Macedonia proper and the extent of control over Paionia was weaker. Sources and coins shows the Paionian had their own kings but most likely under some vassal or tributary status.