Expansion of Macedonia under Philip II
The Third Sacred War (often just called 'the' Sacred War) broke out in 356 BC, and would present Philip with his first real opportunity to expand his influence into the affairs of central and southern Greece. The war was ostensibly caused by the refusal of the Phocian Confederation to pay a fine imposed on them in 357 BC by the Amphictyonic League, a pan-Greek religious organisation which governed the most sacred site in Ancient Greece, the Temple of Apollo at Delphi. Behind the religious element, there probably lay a display of "realpolitik" in bringing charges against the Phocians, instigated by the Thebans. At this time, Thebes controlled a majority of the votes in the council, and at the autumn meeting in 357 BC, the Thebans were able to have both the Phocians (for the cultivation of the sacred land) and the Spartans (for occupying Thebes some 25 years previously) denounced and fined. Since the fines for both parties were "unjustifiably harsh", the Thebans probably expected neither party to pay, and thus to be able to declare a "sacred war" on either.
Third Sacred War
In response to Philomelos's retreat, Pammenes ordered the Amphictyonic force to cross into Phocis as well, probably by the Fontana pass, in order to prevent Philomelos marching on Boeotia. The two armies converged on Tithorea (whose acropolis, Neon, gives the battle its name), where the Amphictyons brought the Phocians to battle. Details of the battle are scant, but the Amphictyons defeated the Phocians, and then pursued the survivors up the slopes of Mount Parnassos, slaying many. Philomelos was injured, and rather than risk capture, threw himself off the mountain, falling to his death. Onomarchos, who was second in command, managed to salvage the remainder of the army, and retreated to Delphi, whilst Pammenes retired to Thebes with the Boeotian army.