For the North, Cumberland Gap was a natural invasion route into the South, providing access to vulnerable railroads and valuable minerals and salt works in East Tennessee and southwest Virginia. For the South, the Gap was a gateway for an invasion of Kentucky to drive out the Federal foe. Cumberland Gap changed hands four times during the Civil War: in August 1861 Confederates fortified Cumberland Gap; on June 18, 1862, Union forces under General Morgan occupied the Gap; on September 17, 1862, Confederate General Stevenson forced the evacuation of Union troops from the Gap as the Confederates' push into northern Kentucky's Bluegrass region began; and on September 9, 1863, Union forces under General Burnside accepted the surrender of General Frazer's 2,300-man Confederate garrison at the Gap. Cumberland Gap remained in Northern hands for the duration of the war.