“Graybacks” was the common name for Pediculus humanus corporis and Pediculus vestimenti–body lice. Per Taber’s Cyclopedic Medical Dictionary, they are “transmitted by direct contact or use of infested wearing apparel, occurs as a result of crowding or unhygienic conditions.” John Billings’ Hardtack and Coffee, describes “skirmishes” with this gray enemy and how every Civil War soldier battled with them, regardless of rank or pre-war social ranking.