Lelantine War

The Lelantine War was a long-remembered military conflict between the two ancient Greek city states Chalkis and Eretria in Euboea which took place in the early Archaic period, at some time between ca 710 and 650 BC. The reason for war was, according to tradition, the struggle for the fertile Lelantine Plain on the island of Euboea. Due to the economic importance of the two participating poleis, the conflict spread considerably, with many further city states joining either side, resulting in much of Greece being at war. The historian Thucydides describes the Lelantine War as exceptional, the only war in Greece between the mythical Trojan War and the Persian Wars of the early fifth century BC in which allied cities rather than single ones were involved.

"The war between Chalcis and Eretria was the one in which most cities belonging to the rest of Greece were divided up into alliances with one side or the other."

-Thucydides (I. 15, 3)