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
After Philomelos's defeat at Neon, the Thebans thought it safe to send the general Pammenes to Asia with 5000 hoplites; Pammenes probably met with Philip at Maroneia in 355 BC, presumably on his outward journey. Buckler, the only historian to produce a systematic study of the sacred war, therefore places Neon in 355 BC, and suggests after the meeting with Pammenes, Philip went to begin the siege of Methone. Other historians have placed Neon in 354 BC, because Diodorus says that the battle took place while Philip besieged Methone which Diodorus (at one point) places in 354 BC. Disregarding the dates, most historians agree upon the same sequence of events for the first phases of the Sacred War. The principal question is therefore when that sequence started. Thus, Buckler (as well as Beloch and Cloche) dates Neon to 355 BC, Methone to 355–354 BC, Philip's first Thessalian campaign to 354 BC, and his second to 353 BC. Conversely, Cawkwell, Sealey, Hammond and others lower all these dates by one year, beginning with Neon in 354 BC.