The Peloponnesian War (431–404 BC) was a conflict between Athens and Sparta for control of the Greek world. Athens was a prominent naval power, while Sparta was considered invincible on land. Pericles, the great Athenian statesman, urged his compatriots to avoid open battle with the famous Spartan soldiers and use their fleet instead to attack their enemies. During the first summer of war the Athenians sent 100 triremes to western Greece, where they took Astakos and expelled the tyrant Euarchus (a friend of Sparta). He persuaded the Corinthians to assist him in taking back the town, something he managed to do the following winter when the Athenians had left for home.