The 54th Virginia and 63rd Virginia Infantry were the only two Virginia regiments in the AoT at the time. They were in Alexander W. Reynold's Brigade. It appears as one company of the 63rd, Company H, was from Wythe County; so perhaps a soldier or correspondent from that company wrote home of that particular incident. Its possible, being that a large portion of Alexander Reynold's Brigade was routed during the attack on Missionary Ridge.
Sam Watkins tells of this incident, he says the soldier just kept running. I believe this is also where Bragg asks a soldier why he's running. His answer, "Cause I Can't Fly ! "