During the Greco-Persian Wars, Athens developed a large, powerful navy in the eastern Mediterranean Sea that defeated the even larger Persian Navy at the Battle of Salamis. The Athenian Navy consisted of 80,000 crewing 400 ships.

Sparta was leader of an alliance of independent states that included most of the major land powers of the Peloponnese and central Greece, as well as the sea power Corinth. Thus, the Athenians had the stronger navy and the Spartans the stronger army.