1861-65 military conflicts between whites and Indians residing in today's Washington, Idaho, and Oregon are occasionally the subject of book length treatments, but no one has attempted a comprehensive Civil War history of the region. From the publisher's description* of his work, it looks like Scott McArthur's The Enemy Never Came: The Civil War in the Pacific Northwest (Caxton Press, Oct 2012) is on the right track.
* - "Although the Pacific Northwest was the area furthest removed from the actual battles of the Civil War, it was nonetheless profoundly affected by the war. The Enemy Never Came examines the everyday lives of the volunteer soldiers who battled Native American renegades of the region and of the settlers who were deeply affected by the war yet unable to do much about it. Pacific Northwest pioneers soon chose sides, most allying with the North, others supporting the southern states’ right to withdraw from the union. Still others attempted to ignore the entire issue of the War between the States, leaving “that problem” to the folks back East. Because communication with the rest of the nation was slow and tenuous during the early years of the war, the early settlers of what is now Oregon, Washington, and Idaho concentrated on controlling the restive Native Americans whose land and society had been overwhelmed by white settlers. These same settlers, however, nonetheless vigorously argued politics and worried about invaders from the South, from the British colonies to the North, and from the sea, none of whom ever materialized."