It is set in England and Cyprus in 1099, at the time of the First Crusade.
Loving the Enemy...
After Judith Coverdale saw her family's estate razed to the ground by Normans, she vowed to avenge her family's honor. She donned a boy's disguise and joined a band of outlaws, led by her brother, to terrorize the invaders.
When disaster struck, Judith found herself in the strong arms of the great warrior Rannulf de Mandeville. What she soon realized was that Rannulf was the brother of the murdering Norman who'd stolen her lands.
Time and time again, Rannulf proved his devotion to her and taught her lessons in survival, but would she ever accept his love?
It was originally published in the UK in 1990. The previous German print edition was a duo with Elizabeth Henshall's, Verrat des Herzens.
This is the cover of the print edition:
And because the changes in cover fashions are interesting, this is the original German cover (from 1991):
And this is the other German edition, (I think it's 1993).