The oath that bound Amphictyonic members to protect Delphi also gave any accusation of sacrilege enormous political weight, and across the Archaic and Classical periods a series of conflicts remembered as the Sacred Wars were fought under the League's banner, formally at least, in its defense. The First Sacred War in the early sixth century BCE was fought against Crisa, a city accused of exploiting pilgrims traveling to the sanctuary, and its outcome, Crisa's destruction and the reorganization of the Pythian Games under Amphictyonic control soon after, is often treated as the moment the League's authority over Delphi took the shape later sources describe.
The most consequential of the later conflicts, the Third Sacred War of the mid fourth century BCE, began over a dispute concerning cultivation of land sacred to Apollo and drew in Thebes, Phocis and eventually Philip II of Macedon, whose intervention on the Amphictyony's behalf against Phocis gave him a foothold in Greek affairs and, through his resulting seat on the League council, a formal claim to a voice in the religious governance of Greece itself, one step in his broader absorption of Greek city-state politics into Macedonian power. A religious body meant to keep any one city from dominating Delphi ended, by the time of Philip, helping a single outside power dominate much of Greece.