The History of Athens and Corinth

In 460 BC, Athens began to open hostilities with various allies of Sparta. The fighting took place in and around the eastern Peloponnesus but nothing decisive happened. Alarmed by Athens' aggressiveness in the Seronic Gulf, Agina entered into the war against them. And so, Pericles exhorted the Athenian Echlesia to wage war with the Agonitans in order to remove Agina as the eyesore of the Pyreus. In the resulting sea battle, the Athenians gained a great naval victory against the combined Aginitan-Peloponnesian fleet - though how many ships were sunk is not given.