The battle of Neon (354 BC) was a battle of the Third Sacred War, and was notable for the death of the Phocian leader Philomelus.
Philomelus was the Phocian leader at the start of the war. Early in the war Philomelus captured the sanctuary at Delphi, and he used the money to pay for a powerful mercenary army. In 355 he defeated a Locrian invasion at the Phaedriades cliffs, near Delphi. In 354 he invaded Locris, where he had some successes, defeating a joint Locrian and Boeotian army in an unnamed cavalry battle, and then defeating a Thessalian army in a battle at the Argolas Hill.
Philomelus's run of success ended at the battle of Neon. The Boeotians had been slow to move, but they now appeared with an army 13,000 strong. Philomelus had his Phocians, his mercenaries, and 1,500 Achaeans who had arrived from the Peleponnese. The two armies settled down into a standoff in the area north of Mount Parnassus, near the Phocian town of Tithorea (also known as Neon).
The Phocians probably occupied the city. During the standoff the Boeotians captured a number of the Phocian mercenaries, who were out foraging. They were then paraded in front of 'the city', and executed as temple robbers. Unsurprisingly this angered the Phocian mercenaries, and they convinced Philomelus to respond in kind. He sent out raids that captured a number of Boeotians, who were then executed. This ended this brief exchange of atrocities.
The standoff must have ended soon after this, as Diodorus informs us that the battle began as both armies were 'invading another district'. The two vanguards clashed while passing through heavily wooded rough country. This encounter battle drew in more troops, but the Phocians were outnumbered, and suffered a heavy defeat. The awkward terrain made it difficult for the defeated Phocians and their mercenaries to escape, and many of them were killed in the retreat. Philomelus himself was eventually trapped at the top of a cliff, and in order to avoid being tortured threw himself off the cliff.
Command of the Phocian army passed to Philomelus's brother Onomarchus, who managed to rally the survivors. The Boeotians decided that the death of Philomelus, who they blamed for plundering the oracle at Delphi, was enough punishment, and would deter the Phocians from further attacks, returned home without taking advantage of their victory. Instead they chose to send an army, commanded by Pammenes, to Asia to support the Persian satraps in their revolt against Artaxerxes III (Satrap's Revolt). The Third Sacred War was thus allowed to drag on for several more years.
Diodorus provides us with the description of the battle (16.31.3), while Pausanias (10.2.4) gives us the location, and repeats Diodorus's version of the death of Philomelus.