Marion Zimmer Bradley - Mists of Avalon

A fantasy book based on Arthurian stories. Continuation of "The Forest House". Part of a series "Avalon"
An epic tale of love, loyality, betrayal, kingship, and magic. It takes place over several decades and generations.  It tales the fabled tale of Camelot and the knights of the round table. Taking a different view from the legend, it is told of the perspective of the women of Avalon. These powerful women use their magic to fulfill the will of the Goddess and place a king on the throne of Britain, as well as later take him down from it...