The battle of Panormus (412 BC) was a minor Athenian victory during the longer siege of Miletus, most notable for the death of the Spartan commander Chalcideus (Great Peloponnesian War).
In the aftermath of the Athenian disaster at Syracuse, the Spartans had decided to encourage revolts across the Athenian Empire. On the Ionian coast of Asia Minor the city of Miletus joined the revolt, with encouragement from the Athenian exile Alcibiades. The Spartans used the city as their main base in the area, and send a small fleet under Chalcideus to support the revolt.
The Athenians reacted quickly, and soon established a blockade of the city. A fleet of twenty ships took up a position on the nearby island of Lade, and waited for reinforcements.
Before these reinforcements arrived, the Athenians on Lade decided to carry out a raid on Milesian territory, and landed at Panormus, to the south of the city. Chalcideus led a small force out to oppose them, but was killed in the resulting battle. The Athenians must have been worried that a larger army was close behind, and so retreated without erected a trophy. They returned three days to do this, but then retreated once again, and the Milesians demolished the trophy on the grounds that it hadn't been erected while the Athenians held the ground after the battle.
The major reinforcements from Athens arrived before the end of the summer, and a larger battle was fought at Miletus. The Athenians and their allies were victorious, but a Peloponnesian fleet arrived just in time to prevent them from taking advantage, and the siege of Miletus had to be abandoned.