The Old Wilderness Road cutting through the Gap was a natural invasion route. For the Confederacy, it led to the rich Kentucky bluegrass country to the north. For the Union, it led to the Northern sympathizers of East Tennessee, and to an opportunity to cut rebel supply lines. In late summer of 1861, the Confederacy seized the Gap (see Kentucky Confederate Offensive Campaign) and made it the eastern anchor of a defense line extending to the Mississippi River. Brigadier General William Churchwell was placed in command, and fortified the garrison during the fall of 1861. He built seven forts on the north facing slope, and cleared the mountains of all trees within one mile of each fort. Needed more elsewhere, the Confederates abandoned the Gap in June 1862.
Union Brigadier General George W. Morgan soon arrived to take possession of the Gap. The 20,000 men under his command began building nine south-facing batteries to repel an invasion. But none came. The Confederates under Lt. General Kirby Smith by-passed the Gap with 12,000 men and moved into Kentucky, severing Morgan's supply line. Without food and still fearing an attack, General Morgan boldly led his men north through enemy territory to safety.
The Confederates returned to the Gap, cleared up the mess General George Morgan and his men left behind, and strengthened the forts. Many skirmishes took place, as Unionists from Tennessee raided the garrison. In September 1863 a Union force under Maj. General Ambrose E. Burnside moved toward the Gap. On September 7, the Yankees destroyed provisions stored at the Iron Furnace. Burnside also deceived the Confederate commander, Brig. General John W. Frazer, into believing that his force was stronger than it actually was. Believing his Confederates to be outmanned, and short of provisions necessary for a long seige, Frazer surrendered his garrison on September 9.
Lining up along the Harlan Road, the Confederates were amazed to see the small force to which they had surrendered. The Gap remained in Union hands until the end of the war. Except for a garrison inspected by Lt. General Ulysses S. Grant in January 1864, when he labeled the Cumberland Gap the "Gibraltar of America," there was little excitement. Meanwhile, the war fought to its end in the South and East.
By the end of the war the Gap had changed hands four times, yet no major confrontation took place here.