The siege of Methymne (406 BC) was a second success for the Peloponnesian fleet commanded by Callicratidas, and saw the loss of a second Athenian stronghold on the coast of Asia Minor.
Callicratidas had been appointed to replace the popular commander Lysander, and had not been greeted with any enthusiasm by his new fleet. He eventually managed to take command of the fleet, which now contained 140 ships, including fifty newly arrived from Allied states. His first move was to capture the fortress of Delphinium on Chios, and he then moved on to attack the Athenian stronghold of Methymne on Lesbos.
This city was held by a stronger Athenian garrison than Delphinium, and held out against a number of assaults. According to Diodorus Siculus the city fell after some of its inhabitants betrayed it to the Peloponnesians, although Callicratidas is described as having broken inside the walls. Xenophon doesn't mention the treachery and instead has the city fall to an assault, although this could have been aided by unmentioned help from within the city.
Callicratidas behaved generously after the fall of the city. Often during the Great Peloponnesian War the entire population of a city was sold into slavery after a storm, but on this occasion only the captured Athenians and existing slaves were sold. Other free-born captives were freed, and control of the city was returned to its inhabitants.
In the aftermath of this success the Peloponnesian fleet nearly intercepted an Athenian fleet under Conon. Nearly half of the Athenian fleet was lost, but the remaining ships managed to escape into Mytilene, where it was blockaded by Callicratidas.