This is the first volume of a history of the U.S. Army Medical Department from the start of the American Revolution to World War I. This book deals with the period when the Medical Department existed only as a wartime expedient and concludes with the passage in April 18 18 of the law that fin ally established the department on a permanent basis. Future volumes will describe all aspects of the medical care of soldiers scattered in small units over the rapidly growing nation and the challenges posed by war in the nineteenth and twentieth centuries. The discipline that governed Army surgeons and their patients enabled them to control treatment and record its results with a precision and regularity impossible in civilian medicine. Thus Army surgeons and the Medical Department played a large role in the progress of medical science, a role not always recognized by the profession, by the scholarly community, or by the public at large. This new history of the Army Medical Department tells the beginning of that story. It is a significant and long needed contribution to the study of military medicine.