Book excerpt: army branches - infantry, artillery, cavalry, and engineers - as well as the service and support branches comprising doctors and nurses, chaplains, musicians, quartermasters, military police, and the many others who have made up the U.S. Army. Insignia worn by all soldiers, such as eagles, devices with the letters US, and other letters and numbers, are also described and illustrated. Historians, military collectors, military reenactors, antique dealers and collectors,