Swordsman of Lost Terra by Poul Anderson — Read

The third book of the Story of the Men of Killorn. How Red Bram fought the Ganasthi from the lands of darkness, and Kery son of Rhiach was angered, and the pipe of the gods spoke once more.

Now it must be told of those who fared forth south under Bram the Red. This was the smallest of the parties that left Killorn, being from three clans only -- Broina, Dagh, and Heorran. That made some thousand warriors, mostly men with some women archers and slingers. But the pipe of the gods had always been with Clan Broina, and so it followed the Broina on this trek. He was Rhiach son of Glyndwyrr, and his son was Kery.