Alcidas was a Spartan admiral during the Peloponnesian War. He was first appointed to lead 40 allied ships in the Spartan expedition to Mytilene in 427 BC. This was part of a double movement meant to hinder the Athenians from sending help to Lesbos, the other part being an allied invasion of Attica. However, the rebellion of Mytilene was crushed before his force could arrive, largely due to the leisurely pace with which Alcidas led the fleet, and he was forced to put into Embatum in Erythrae seven days after the town capitulated. Alcidas was then urged by , an Elean, to attack Mytilene anyway, as the Athenians would most assuredly be taken by surprise, but Alcidas acted with typical Spartan hesitance and refused. Trying another approach, some Ionian exiles advised him to capture a town in