Cleomenes I defeated the Argives at the Battle of Sepeia around 494 BCE. The battle took place during Sparta’s conflict with Argos and became one of Cleomenes’ major military victories.
Herodotus describes Cleomenes using a signal associated with the enemy’s meal break. When the Argives responded to the signal, the Spartans attacked. Ancient sources give a traditional figure of about 6,000 Argives killed, but that number may be exaggerated and should be treated cautiously.
The defeat severely weakened Argos, Sparta’s important rival in the northeastern Peloponnese. Cleomenes later became involved in political and religious controversy at Sparta and died under unusual circumstances. Sepeia is sometimes confused with later Spartan-Argive battles, but it belongs to the early fifth century BCE.