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.

Sources

Intact and relatively detailed histories of Greece, such as Herodotus's The Histories, Thucydides's History of the Peloponnesian War, and Xenophon's Hellenica cover the period from roughly 500–362 BC. No extant history specifically covers the relevant period of Greek history (359–336 BC), although it is included within various universal histories.. The main source for the period is Diodorus Siculus's Bibliotheca historica, written in the 1st century BC, which is therefore a secondary source.. Diodorus devotes Book XVI to the period of Philip's reign, but the action is much compressed, and due to the scope of the work, this book also contains details of happenings during the same period elsewhere in the ancient world. Diodorus is often derided by modern historians for his style and inaccuracies, but he preserves many details of the ancient period found nowhere else.; . Diodorus worked primarily by epitomising the works of other historians, omitting many details where they did not suit his purpose, which was to illustrate moral lessons from history; his account of the period therefore contains many gaps..

Another surviving work for the period is Justin's epitome of Pompeius Trogus's Philippic History. Justin's epitomised history is also much condensed from the no-longer-extant original and covers not only Philip's reign, but also the history of Macedon before him, the exploits of Philip's son, Alexander the Great, and his diadochi successors during the Hellenistic period.; . These surviving histories are complemented by fragments of other histories, including Theopompus's 58-volume history of Philip (which was the source for much of Trogus's Philippic History) and by contemporary epigraphic sources.; .

Outside the brief notices of Philip's exploits which occur in Diodorus and Justin, further details of his campaigns (and indeed the period in general) can be found in the orations of Athenian statesmen, primarily Demosthenes and Aeschines, which have survived intact. Since these speeches were never intended to be historical material, they must be treated with great circumspection, particularly given the identity of the authors. Demosthenes and Aeschines have been described as "a couple of liars, neither of whom can be trusted to have told the truth in any matter in which it was remotely in his interest to lie".. For instance, the Peace of Philocrates (made in 346 BC) is known primarily from their speeches (both called On the False Embassy), made in 343 BC, when Demosthenes prosecuted Aeschines for his involvement in making the peace treaty.. In his speech, Aeschines poses as the champion of the peace treaty, when he had in fact opposed making peace; conversely, Demosthenes, who had been a proponent of peace in 346 BC represents himself as part of the "war-party". The arguments made in the speeches therefore refer to the political situation in 343 BC and not the situation when the treaty was made, which makes teasing out the actual historical threads rather difficult.

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.Diodorus, XV.55.Plutarch. Pelopidas, 23; Xenophon. Hellenica, 6.4.

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.Xenophon. Hellenica, 7.5. 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:

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.Diodorus, XVI.2 . 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".Diodorus, XVI.3 . 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