The Chians sent delegates to Athens so they could be allied with the city of Athens since the cities of the Minor Asia and the islands were under the threat of the Persians invading them according to the treaty of Antaklidios Peace. The Athenians accepted the proposal and so Chios entered the Second Athenian alliance (377 B.C.). The treaty ensured the freedom and the autonomy of the allies and set an example for the terms of the treaty that the Athenians contracted with the other cities. Athens managed to gain again the sovereignty in the Aegean Sea with the help offered by the island of Chios and the other allies.

After the victory of the Thebans in the region of Leuktra (371 BC.), Epaminondas incited the islands of Rhodes and Chios, which had the most powerful navies, to help him. The citizens of Rhodes and Chios that were dissatisfied with the Athenians agreed to help him. Epaminondas’s first victory was outside in the harbour of Chios, where Athenian fleet suffered a crushing defeat. However, there was no succession in his victory and later he was killed in the battle of Mantinea (362 B.C.). After his death, Chios returned to the Athenian alliance.