The rise of Macedon , including its conquest and political consolidation of most of Classical Greece during his reign, was achieved by his reformation of the army the establishment of the Macedonian phalanx that proved critical in securing victories on the battlefield , his extensive use of siege engines, and his use of effective diplomacy and marriage alliances. After defeating the Greek city-states of Athens and Thebes at the Battle of Chaeronea in BC, Philip II led the effort to establish a federation of Greek states known as the League of Corinth , with him as the elected hegemon and commander-in-chief [ 4 ] of Greece for a planned invasion of the Achaemenid Empire of Persia.
However, his assassination by a royal bodyguard, Pausanias of Orestis , led to the immediate succession of his son Alexander, who would go on to invade the Achaemenid Empire in his father's stead. While in Thebes, Philip received a military and diplomatic education from Epaminondas , and lived with Pammenes , who was an enthusiastic advocate of the Sacred Band of Thebes.
In BC, Philip returned to Macedon. Before leaving, Perdiccas had appointed Philip as regent for his infant son Amyntas IV , but Philip succeeded in taking the kingdom for himself. Philip's military skills and expansionist vision of Macedonia brought him early success. He first had to remedy the woes over Macedonian territory faced by his throne's government. This was a predicament that had greatly worsened through Macedonia's defeat by the Illyrians , a struggle in which King Perdiccas himself had died.
The Paeonians and the Thracians had sacked and invaded the eastern regions of Macedonia, while the Athenians had landed at Methoni on the coast with a contingent under the Macedonian pretender Argaeus II. Philip pushed back the Paeonians and Thracians promising tributes, and defeated the 3, Athenian hoplites BC. Momentarily free from his opponents, he concentrated on strengthening his internal position and, above all, his army. Philip II made many notable contributions to the Macedonian army.
The cavalry, which were the primary source of the army's strength, went from a force of to from the time of the battles with the Illyrians to BC. In addition to these changes, Philip created the Macedonian phalanx , an infantry formation that consisted of soldiers all armed with a sarissa. Philip is credited for adding the sarissa to the Macedonian army, where it soon was the common weapon used by most soldiers. Philip had married Audata , daughter or granddaughter of the Illyrian king Bardylis.
