Eagle and the Raven — Pauline Gedge

They marked time by the moon and counted nights, not days. They measured their history in "ages" of 30 years, passing on all knowledge and lore by recitation. A mysterious and passionate people, the Celts in first-century Britain fought and loved with equal intensity, governed in their conduct by a stern code of honor and fierce loyalty to their mother tribes and to their island world, Albion.
Caesar had come and gone, but Claudius was intent on conquest. Under the banner of the Eagle of Rome, Britannia's invaders advanced like a plague--pillaging, raping, burning.
Spanning three generations, this book is the story of Caradoc, son of a Celtic king, who sets out to unite the people of the Raven and lead them against Rome. It is about Eugrain, his gentle wife, who, left alone for months at a time, can only seek solace in Caradoc's best friend. It is about Gladys, Caradoc's warrior sister, who, despite her fierce spirit, falls in love with the Roman general who is her captor; and about Aricia, the vain and soft-living queen of a northern tribe. Once spurned by Caradoc, she has sworn revenge and aligns herself with Rome. Finally, it is the story of Boudicca, a strong-willed woman who takes up the cause that was Caradoc's legacy.