The two armies met in territory previously seized by the Illyrians, in order to settle their dispute by determining which of the two forces was the mightiest. The Illyrians were known for their tribalism and ferocity in combat. After previous victories over the Macedonians, and proving themselves capable conquerors, there likely wasn’t much apprehension about meeting them again in battle, though they may have wondered why the Macedonians decided to challenge them again so soon after their last crushing defeat. How much could the situation in Macedon have changed in only a year?

The Macedonians shared much in common with the southern city-states of Greece, including combat strategy and tactics. Though they claimed to be descendants of Heracles, much like the Spartans, some southern Greeks did not consider Macedonians to be truly Greek, and sometimes referred to them as barbarians. At the same time, the Argead royal house of Macedon participated in Panhellenic institutions, worshiped Greek gods, and Macedonian culture had substantial connections to the wider Greek world. Times change, however, and while the Macedonians had much to prove, their new king understood well the past failures that allowed Macedon to be perceived as suitable to be taken advantage of.

As the battle began, with both sides nearly equal in number and facing each other like a person standing in front of a mirror, it became clear that there was no equal reflection. The Macedonian army the Illyrians had crushed only a year earlier was no longer the same fighting force. Traditionally, the Macedonians, as well as the Greek city-states, used the dory, a 7-8-foot long spear. The Macedonian infantry, however, was undergoing a transformation. The traditional dory was increasingly giving way to a new weapon that would eventually become synonymous with Macedonian warfare—the sarissa, a two-handed pike ranging from eighteen to twenty-two feet long. Its extraordinary reach allowed several ranks of spear-points to project beyond the front of the formation, making it extremely difficult for enemy infantry armed with shorter weapons to close the distance. Because the sarissa required two hands to operate, some defensive capability was sacrificed for far greater reach.

The phalanx was designed to hold enemy infantry in place, creating opportunities for cavalry and light infantry to strike vulnerable flanks. The Macedonians were also transforming into a well-trained and increasingly professional army capable of great discipline and focus during battle.

With the advanced Macedonian capabilities beginning to be employed in battle, it wasn’t long before the Illyrians, who very recently destroyed the Macedonians, realized they were now completely outclassed in a rather unexpected turn of events. According to the ancient historian Diodorus, approximately 7,000 Illyrians were killed before the battle was over. The army that had crushed Macedon only a year earlier had now suffered a devastating defeat of its own.

Macedon had survived. Its enemies had been driven back. But Philip's ambitions were beginning to extend beyond merely defending his kingdom. To the south lay a Greece still divided by rivalries, alliances, and old grievances — the same divisions he had observed firsthand during his years in Thebes. There, Philip had also learned lessons about warfare that would help him rebuild Macedon's broken war machine. In time, Philip would attempt something no Greek power had permanently achieved: bringing the city-states beneath a common order. His strategy — by any means necessary.