Grand Caverns, known as Weyers Cave during the Civil War, was discovered in 1804 and soon became famous. During the Shenandoah Valley campaigns of 1862 and 1864, several Union and Confederate soldiers visited the caverns. For almost a week beginning on June 12, 1862, after the Battles of Cross Keys and Port Republic, Confederate Gen. Thomas J. "Stonewall" Jackson's army camped along the South River between Weyers Cave and Mount Meridian. The men enjoyed a much-needed rest after Jackson's famous campaign, during which Union forces were defeated, and some entertained themselves with candlelit tours of Weyers Cave. By June 18, Jackson's men were marching east to join their commander in the defense of Richmond, the Confederate capital. In 1864, Union Gen. Philip H. Sheridan directed a Shenandoah Valley campaign that became famous for its destruction of mills and barns in the autumn. The 14th Pennsylvania Cavalry bivouacked near Weyers Cave on September 26-27, a week after the Third Battle of Winchester, while pursuing the wagon train of Confederate Gen. Jubal A. Early's retreating army. Capt. William W. Miles, Co. I, visited the cave and wrote his name on a wall inside on September 26, 1864. The next day, a Confederate attack drove the Pennsylvanians away. More than 230 Civil War-era signatures have been identified on the cave walls. Grand Caverns was designated a National Natural Landmark in 1973.