Her Majesty's Yankee (The Civil War Trilogy Book #1)

Cashiered from Queen Victoria’s Army of India for standing up for his native soldiers against an unfeeling general with royal connections, John Whyte, the youngest son of the Duke of Brandon,  finds himself at loose ends with no prospects.  The American Civil War is raging, so he comes to America and convinces President Lincoln to commission him in the Union Army.  He is quickly involved in busting up the spy ring of Rose Greenhow, a notorious Confederate spy.  As a reward, Lincoln sends him west to report on General Grant and his fitness as a senior commander.  He completes his mission, praising Grant and earning Grant’s goodwill.  He then takes command of a regiment of the Michigan Volunteer Cavalry, under none other than Custer, the boy general of the Union Army, where his adventures are just beginning.