The siege of Mytilene (406 BC) saw the Peloponnesians attempt to capture this Athenian held city on Lesbos. The siege was ended by the Athenian naval victory at Arginusea, but the reaction to the aftermath of this battle played a part in the final Athenian defeat in the Great Peloponnesian War.
In 407 the Peloponnesian fleet had been commanded by the popular Lysander, but at the end of his year of service he was replaced by Callicratidas. Callicratidas took command of a fleet of 140 warships, much larger than the Athenian fleet of seventy ships commanded by Conon. The Peloponnesians began the campaign with a string of successes. First they captured the Athenian fortress at Delphinium, in the territory of Chios. Next he attacked Teos, before moving on to besiege the Athenian garrison of Methymne on Lesbos.
Conon had put to see in an attempt to help the defenders of Methymne, but when he discovered that the city had fallen he camped on one of the 'Hundred Isles', or Hecatonnesia, an island group to the south of the Gulf of Adramyttium, east of Lesbos. This gave the Peloponnesians a chance to cut the Athenians off from their base on Samos, further south along the coast of Asia Minor. Callicratidas attempted to take advantage of this chance, put to sea and headed for the Athenian position.
The two fleets sighted each other at daybreak. Conon decided not to risk a battle against a fleet twice as large as his own, and instead attempted to reach safety at Mytilene, an Athenian-held city on Lesbos. The Peloponnesians were right on his heals, and a battle was fought inside the harbour of Mytilene (quite a large sheltered area between the city and the main part of Lesbos). In the resulting naval battle the Athenians lost thirty ships, although most of the crews escaped to shore.
Callicratidas now settled down to conduct a siege of the city. Xenophon gives a short account of this siege, focusing on the lack of food in the city and Conon's efforts to get a message to Athens. He eventually achieved this by preparing two of his fastest ships, waiting for five days until the enemy's guard was down, and then ordering them to dash out to sea. One ship headed out into open waters but was captured, while the second ship successfully reached the Hellespont and from there Athens.
Diodorus Siculus gives a somewhat different account of events. In his version the first naval battle was deliberately brought on by Conon, although the result was the same. This was followed by a second naval battle in the harbour, and only after this did the siege begin.
When the news reached Athens a great effort was made to raise a new fleet. Both Diodorus Siculus and Xenophon say that the Athenians were able to bring together a fleet of 150 ships, some from Athens, some from Samos and some from the islands within the Empire. This fleet advanced up the coast from Samos to the Arginusae Islands, on the coast to the east of Lesbos. Callicratidas came out to intercept the Athenians, but the resulting battle of the Arginusae Islands was a clear Athenian victory. Unfortunately bad weather prevented the admirals from rescuing many survivors of the fighting. This caused a scandal in Athens, where six of the eight admirals were executed. This left Athens without any experienced commanders in the following year, and this inexperience probably played a role in the crushing Athenian defeat at Aegospotami that effectively ended the war.