Blue Horse Dreaming by Melanie Wallace
'I will not live amongst you' are the only words Abigail Buwell will speak when she arrives at Fort 2881. She has been taken from her life among the savages and returned against her will to 'civilisation' - the last military outpost on the hellish frontier's edge in the aftermath of the American Civil War. Alone and heavily pregnant, she is watched day and night by her beloved blue roan horse.
Major Cutter, the commander into whose hands Abigail is delivered, is crushed by the war and its aftermath and haunted by the ghost of a boy from his past. As the fort descends into madness and chaos, and Abigail's resistance to redemption continues, Cutter's fate and that of his silent charge are bound together.