One Vast Hospital contains a general introduction to Civil War hospitals and staffing, a list of the doctors and stewards at each Frederick hospital, the history of the hospital site, complete with photographs, and a complete Hospital Patient List from after the battles of South Mountain and Antietam. The Hospital Patient List contains nearly 10.000 individuals and includes their name, rank, regiment, company, complaint, date of admission, date discharged from hospital, and comments. The list is a great source for genealogists and historians.