Opponent of Athens in the Peloponnesian War

SPARTA

This ancient city-state was known for its disciplined warriors and oligarchic government, famously defeating Athens with Persian support in the 5th century BC.

This clue refers to the famous conflict between two ancient Greek city-states, where Sparta led the Peloponnesian League against Athens. The Peloponnesian War lasted from 431 to 404 BCE, and Sparta emerged as the dominant power after defeating Athens. The answer is straightforward—no wordplay here—just a direct historical reference to Athens' main rival. If you know your Greek history, Sparta is the obvious choice.