In August 338, the Macedonian king Philip had defeated an army of Athenians and Thebans on the plain of Chaeronea, a town in Central Greece (story). The Macedonian victory meant the end of the independence of the Greek towns: Philip forced them to join the Corinthian league.
The Roman author Marcus Junianus Justinus - in English better known as Justin - gives a description of the first meeting in his Excerpt of the History of Philip by Pompeius Trogus.
After he had settled matters in Greece, Philip ordered that envoys should be summoned to Corinth from all the states with a view to consolidating the settlement. He there propounded a covenant of peace for the whole of Greece, giving each state the share that it deserved, and he created a council of representatives to serve as a sort of common senate.
Only the Spartans refused to have anything to do with the king or with the covenant; they considered that a settlement imposed by the victor instead of being agreed on by the states concerned meant enslavement, not peace.
Next, the military contributions were fixed that the individual states were to make, whether to assist the king against attack or for making war under his command. But everyone realized that these arrangements were directed against the Persian empire.note[Justin, Epitome 9.5; tr. Michael Crawford and David Whitehead.]
The text of the treaty has partly been preserved. The first line runs like this:
I swear by Zeus, Earth, Sun, Poseidon, Athena, Ares, and all the gods and goddesses.
- I will abide by the peace;
- I will not break the agreements with Philip the Macedonian;
- nor will I take up arms with hostile intent against any one of those who abide by the oaths either by land or by sea.
The provisions of the treaty were:
- that the constitutions of the member states would remain unchanged;
- that violence between the member states was no longer permitted;
- that, in case of the overthrow of a government, a congress of representatives, was to meet at Corinth;
- that it would establish the facts and declare war;
- that the league's army was to be commanded by Philip;
- that the league's member states would sent a number of soldiers to the league's army in proportion to their size.
Alexander the Great took units of the Corinthian League with him when he invaded the Achaemenid Empire.