Niall of the Nine Hostages plots against Ys. He approaches an oakenshaw, seeking a sign:
"Suddenly upward from it flapped a bird."
-Poul and Karen Anderson, Dahut, Chapter XV, section 4, p. 341.
We are hopeful because we know that Queen Forsquilis of Ys spies afar in her Sending as an eagle owl. And Niall is apprehensive:
"Knuckles whitened on his spearshaft, breath hissed between his teeth." (ibid.)
However, he is immediately reassured:
"But this was no eagle owl such as had gone by on an unlucky eventide. This was a raven, eerily belated for one of its kind and huge." (ibid.)
The eagle owl had flown by at sea. This raven is seasonally late and oversized. So that there can be no doubt:
"Thrice its blackness circled above Niall's spearhead, before it wheeled and winged away south." (ibid.)
Niall accepts the sign joyously and his men make signs against the Morrigu. That Goddess had helped the Hivernians to escape from Ys just as Mithras later helped the Ysans to scatter the Franks. Gods are on the move.
In Ys, Niall, who wants the destruction of Ys, will pose as an inoffensive trader. He is bound to attract the attention of Dahut, who wants the destruction of the Ysan King. She will suffer the same disappointment that she did with Gunnung but on a vaster scale.