The Lelantine War, a military conflict between the two Greek city states Chalkis and Eretria, takes place sometime between circa 710 and 650 BCE.

The eponymous reason for war is, 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 spreads 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 the most widespread war in Greece between the mythical Trojan War and the Persian Wars of the early fifth century BCE.

"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)