Historical Marker #521 in Bell County notes the importance of the Cumberland Gap during the American Civil War.
Cumberland Gap is located on the route of the famous old "Wilderness Road," one of the entry points into Kentucky during the pioneer period. Desired for its geographic position in the Appalachian Mountains and an advantageous connection between the eastern and western theaters of the Civil War, Cumberland Gap changed hands a number of times during the conflict.
This key passageway, sometimes referred to as the "Gibraltar of America," was first held by the Confederates, who built earthwork fortifications under the supervision of General Felix K. Zollicoffer in the fall of 1861. After being defeated at the Battle of Mill Springs on January 19, 1862, where Zollicoffer was killed, the Confederates continued to hold the Gap as the eastern anchor of their defensive line that stretched across southern Kentucky to the Mississippi River. When the southern forces were ordered to Chattanooga's defense in the summer of 1862, the Gap was abandoned to Union forces under the command of General George Morgan, who further strengthened its fortifications. Morgan chose to desert Cumberland Gap in September 1862, when a Confederate force under General Edmund Kirby Smith invaded Kentucky. Although the Confederates retreated from Kentucky after the Battle of Perryville, they continued to hold the Gap until the late summer of 1863, when General Ambrose Burnside launched an invasion of East Tennessee designed to capture Knoxville. This offensive also captured the Gap along with more than two thousand Confederate prisoners. Union forces controlled the Cumberland Gap for the remainder of the war.
Soldiers on both sides despised occupation duty at Cumberland Gap. The winter winds were brutal and the summer sun, due to the denuded landscape, proved unrelenting. Opposing combatants understood all too well that the Gap's advantageous defensive topographical features made it easy to defend, yet at the same time made it vulnerable to siege. The location was almost impossible to hold when supply and communication lines were severed. However, for much of the war both sides coveted the Gap. For the Confederates the Gap's strategic location promised a prime route into the resource-rich Kentucky Bluegrass Region. To the Federals it was strategic in that it offered an important invasion route into East Tennessee and northern Georgia, as well as an avenue for loyal East Tennesseans to come into Union held Kentucky to enlist.