Siege engines in the context of "Projectile"

Under the reign of Philip II (359–336 BC), the ancient 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 and the subsequent Hellenistic period. 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, Philippopolis (modern Plovdiv, Bulgaria), Herakleia Sintike (Pirin Macedonia, 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 Kingdom of Macedon possessed one of the greatest armies in the ancient world. It is reputed for the speed and efficiency with which it emerged from Greece to conquer large swathes of territory stretching from Egypt in the west to India in the east. Initially of little account in the Greek world, it was widely regarded as a second-rate power before being made formidable by Philip II, whose son and successor Alexander the Great conquered the Achaemenid Empire in just over a decade's time.

The latest innovations in weapons and tactics were adopted and refined by Philip, and he created a uniquely flexible and effective army. By introducing military service as a full-time occupation, Philip was able to drill his men regularly, ensuring unity and cohesion in his ranks. In a remarkably short time, this led to the development of one of what was among the world's finest military machines for the era. Tactical improvements included the latest developments in the deployment of the traditional Greek phalanx made by men like Epaminondas of Thebes and Iphicrates of Athens. Philip improved on these military innovators by using both Epaminondas' deeper phalanx and Iphicrates' combination of a longer spear and a smaller and lighter shield. However, the Macedonian king also innovated; he introduced the use of a much longer spear, the two-handed pike. The Macedonian pike, also known as the sarissa, gave its wielder many advantages both offensively and defensively. For the first time in Greek warfare, cavalry became a decisive arm in battle. The Macedonian army perfected the co-ordination of different troop types in an early example of combined arms tactics—the heavy infantry phalanx, skirmish infantry, archers, light cavalry and heavy cavalry, and siege engines were all deployed in battle; each troop type being used to its own particular advantage and creating a synergy of mutual support.