Chalcidian League

[7] In the spring of 432 BCE, during the first phase of the Peloponnesian War, several cities of Chalcidice broke away from the Athenian-dominated Delian League.

The inhabitants of these cities abandoned them and moved to Olynthos in an act of synoecism, forming a single state and adopting the demonym "Chalcidians".

[10] In the aftermath of the Peace of Nicias, the city-states of Argilus, Akanthos, and Stageira, as well as other unnamed ones, joined.

Nevertheless, when the question was put, fear of annoying Sparta ensured that the proposal was carried, and a force of 10,000 was authorized to be sent.

[16] Freeman regards the Spartan dissolution of the League as one of the most "calamitous events" in Hellenic history for, in his view, the League uniting the northern Greek cities with the most Hellenised cities of Macedonia would have prevented the rise of Philip II of Macedon.

[18] They soon fell out with Athens over control of Amphipolis, and in the subsequent war lost a number of cities, including Torone and Potidaea.

The League had a federal citizenship, common laws, foreign policy, coinage, and military.