The unit defended the border between Virginia and both Tennessee and Kentucky, particularly the strategic Cumberland Gap and the strategic resources of lead mines and salt works at Saltville, Virginia. The Cumberland Gap was initially fortified by Confederate General Felix Zollicoffer (a former Tennessee Congressman), and contested by Unionist Tennessean Capt. Powhatan Carter. Although Zollicoffer was killed in action in the January 1862 during the first Kentucky invasion, Union Generals George H. Thomas and later William T. Sherman had difficulty securing the Cumberland Gap. At Pound Gap in nearby Wise County, Virginia, Slemp was among the Confederates opposed by Union Col. (later General and President) James Garfield, who forced their retreat.