Department of the East (Pre-war)
Major General John E. Wool
All of the United States east of the Mississippi not in other departments.
At the beginning of the Civil War the United States Army consisted of a little over 16,300 officers and men in 5 mounted regiments, 4 artillery regiments and 10 infantry regiments. They were scattered in small one and two company outposts across the continent. With the exception of a few artillery companies in east coast forts, none of them were in a posiition to easily reach, much less defend, the nation's capital.