Buffalo soldier
(Junior Book, Reference)

At the end of the American Civil War, Charley - a young African-American slave - is ostensibly freed. But then her adopted mother is raped and lynched at the hands of a mob and Charley is left alone. In a terrifyingly lawless land, where the colour of a person's skin can bring violent death, Charley disguises herself as a man and joins the army. Soon, she's sent to the prairies to fight a whole new war against the 'savage Indians'. Trapped in a world of injustice and inequality, it's only when Charley is posted to Apache territory that she begins to learn what it is to be truly free.