Marion Zimmer Bradley's ancestors of Avalon

"When Rome invades, Lhiannon joins the Druids, devoting her powers to the fight, while Boudica marries Prasutagos, a king who has accepted the empire's rule to keep his people safe. But when he dies, the Romans brutalize Boudica and her daughters. In rage, Queen Boudica raises the British tribes and nearly succeeds in driving the Romans from Britain, claiming a place in history. Lhiannon, a warrior in her own way, survives years of conflict, with Rome and within herself, to become the guardian of the Druid traditions in the new Roman Britain as high priestess of the Forest House."--BOOK JACKET.