Born of the Sun by Joan Wolf.

"Born of the Sun"
Penguin Books
Language: English
Published in 1991, first Onyx printing. Previously published in 1989.
Contains the novel Born of the Sun by Joan Wolf in 508 pages.
"This compelling saga about a beautiful Celtic princess who gives her heart to a Saxon prince explodes with the passions of love and war. When the Saxon army, in its bloody charge against the Celts, captures the child-princess Niniane, they bring her to Cynric, King of the West Saxons. Enchanted by her innocence and beauty, he makes Niniane a favored prisoner. But she soon discovers that the King's court abounds with tempestuous intrigues and tormented rivalries. And when the adulterous and envious Queen arranges for a duel between the King's beloved illegitimate son and her own son, heir to the throne, intrigue turns to deadly perild. With this epic novel of the star-crossed passion that swept the Celts and Saxons to the brink of war - and two lovers to the edge of oblibion - Joan Wolf brilliantly brings alive a little-known but fascinating age."