The Battle of Kerkis was a battle of the Peloponnesian War which was fought in Messenia in 422 BC.
The Spartan victory at the Battle of Akrona checked Athens' advances on the Greek mainland; Boeotia's return to the Peloponnesian League stymied Athens' ambitions to become the predominant power in central Greece. The Spartans proceeded to embark on a counteroffensive in the Peloponnese, where the Athenians utilized the naval base of Pylos in Messenia as a staging ground for raids against Laconia. The Spartan military launched an invasion of Messenia after the mercenary Kassandra assassinated the pro-Athenian King Chromios the Wit's Edge. In the ensuing battle, Kassandra fought as Sparta's champion, while Kaletor the Flower fought for Athens. Kassandra went on to slay Kaletor, 5 Athtenian captains, and 21 soldiers, turning the tide of battle in Sparta's favor. The Spartan victory drove the Athenians out of a key region of the Peloponnese, confining them to Achaea.