From fairly early on, Philip III had begun to lay plans, in many ways similar to projects endorsed by orators of the day, for the conquest of Asia Minor. The first step was to end the civil wars among Greeks. This was achieved once Philip had assumed control of the entire country after the battle of Chaironeia (338 BC). In 337 BC, Philip invited the Greek cities to conclude a peace treaty at the Isthmus of Corinth.
A year later, an offensive alliance (the League of Corinth) was also established, with the objective of uniting the Greeks in preparation for a campaign against Persia. The pretext for this aggressive move was to punish the Persians for the destruction of Greek sanctuaries, although in fact Philip was aiming at consolidating his dominant position among Greeks.