 The Athenians, aware of their naval superiority, never expected an open naval attack against the Piraeus.As a result, there was no fleet positioned to defend the port.Although the execution of the Megarian plan initially seemed to go well, on the night that the Spartans began to sail to the Piraeus, they became afraid of the risk involved and altered their plan to the less ambitious goal of attacking the Athenian fort on Salamis.