Corinth, Thebes, Sparta.
Sparta and Athens vied for supremacy .
Elites in Halo: CE and the first half of Halo 2; Brutes for the second half of Halo 2 and all of Halo 3.
Sparta and Athens joined 20-odd other Greek city-states to oppose Persia. After that war,the Peloponnesian League led by Sparta fought the Peloponnesian War against the Athenian empire.
In ancient times, Sparta was the leading rival of Athens
corinth
Corinth
Spartans
Spartans
No British counties fought against each other in ww1 England, Wales And Scotland All Fought Against The Germans/Austro-Hungarians In The First World War.
Athens
Yes
Sparta