The First Sacred War is fought between the Amphictyonic League of Delphi and the city of Kirrha.

The conflict has arisen due to Kirrha's frequent robbery and mistreatment of pilgrims going to Delphi and their encroachments upon Delphic land.

The war, which results in the defeat and destruction of Kirrha, is notable for the use of chemical warfare at the siege of Kirrha, in the form of hellebore being used to poison the city's water supply.