Here Lies Arthur
by Philip Reeve
The novel starts with an attack by Arthur and his war-band, and the escape of Gwyna, a servant girl. She is found by Myrddin, a bard who hopes to build Arthur's reputation as a great hero so that he can unite the native British against the Saxons who have occupied the east of the country. Myrddin tells Gwyna to give Arthur Caliburn while pretending to be the Lady of the Lake. When she does that successfully, Myrddin disguises her in boy's clothes so that she can travel with the war-band as his servant.
During her travels, she meets a boy who was brought up as a girl, tricks a holy man, swims in the Roman baths of Aquae Sulis, takes part in a battle, and witnesses Arthur's brutality, piety and immorality, all the while observing her master create the fantastic stories that have made 'King Arthur' one of the most famous men in legend. After Arthur's death she creates some stories herself, conceding that the legend is more important than the mere facts.