Andre Norton 
Rebel Spurs 

In 1866, only men uprooted by war had reason to ride into Tubacca, Arizona, a nondescript town as shattered and anonymous as the veterans drifting through it. So when Drew Rennie, newly discharged from Forrest’s Confederate scouts, arrived leading everything he owned behind him-his thoroughbred stud Shiloh, a mare about to foal, and a mule-he knew his business would not be questioned… (Excerpt from Goodreads)