Battle of Crocus Field
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 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
However, Philomelos's embassies elsewhere met with failure. The Locrians demanded that the Amphictyons avenge them and Apollo, and the Thebans sent embassies to the other council members suggesting that a sacred war should be declared against Phocis. This was assented to by most Greek states, including the Amphictyonic council members (minus Sparta and Athens), and those well-disposed to Thebes; furthermore, otherwise uninvolved states declared support for the Amphictyonic for reasons of piety. The Amphictyons seem to have decided that the year was too advanced to begin campaigning, and so agreed to launch military action the following year. They may have hoped that in the meantime, their sacrilegious behaviour would cause the Phocians to reconsider their position.