In Clonard Cormac’s Druid, Cith Rua, meets Fios Mac Athfhis, the Chief Druid of Leinster.
Cith Rua, one of Cormac’s old druids, left the camp that night and went towards the southwest until he met a stream. On the other side of the stream he saw Fios Mac Athfhis from Leinster, the chief druid of the area.
The Druids spoke about the march. Both agreed that Cormac would not be successful in his attempts to get tribute from the men of Munster and compensation for the death of his father, and that Cormac’s people would suffer greatly as a result.
They were overheard by servants who reported the conversation to Cormac.
Cormac ordered that his Druid, Cith Rua, be killed. This was revealed to Cith Rua and he
returned to camp disguised.
The army followed Fios Mac Athfhis, the Leinster Druid who had headed in a southwards direction, but he blew a magic breath on them. He made everyone in the army appear to look like himself, the grey-haired Leinster Druid. The men turned and tried to wound and kill each other.
Cormac called on his fairy druids for help and they blew a magic breath on the army and the men returned to their own form.
The Siege of Knocklong: 250AD 