The Battle of Devil's Backbone, also known as the Action at Devil's Backbone, was a military engagement in the Trans-Mississippi Theater of the American Civil War. Devil's Backbone is a ridge in the Ouachita Mountains approximately 4 miles (6.4 km) southwest of Greenwood, Arkansas. The battle was fought on September 1, 1863, in Sebastian County, Arkansas. The Union victory ensured the safety of the Fort Smith garrison until the end of the war.

The Ouachita Mountains, simply referred to as the Ouachitas, are a mountain range in western Arkansas and southeastern Oklahoma. They are formed by a thick succession of highly deformed Paleozoic strata constituting the Ouachita Fold and Thrust Belt, one of the important orogenic belts of North America. The Ouachitas continue in the subsurface to the northeast, where they make a poorly understood connection with the Appalachians and to the southwest, where they join with the Marathon uplift area of West Texas. Together with the Ozark Plateaus, the Ouachitas form the U.S. Interior Highlands. The highest natural point is Mount Magazine at 2,753 feet (839 m).