This force was quite small compared to the massive state-raised volunteer forces that comprised the bulk of the Union Army. The combat arms included infantry, cavalry, artillery, and other such smaller organizations such as the United States Marine Corps, which, at some times, was detached from its navy counterpart for land based operations. Hardee's "Rifle and Light Infantry Tactics" (1855), the primary tactics for riflemen and light infantry in use immediately prior and during the Civil War, there would typically be, within each regiment, ten companies, each commanded by a captain, and deployed according to the ranks of captains.
The Union Army was the land force that fought for the Union during the American Civil War, 1861 to 1865.
It included the permanent regular army of the United States, which was augmented by massive numbers of temporary units consisting of volunteers as well as conscripts.
Lincoln's call forced the border states to choose sides, and four seceded, making the Confederacy eleven states strong.
The war proved to be longer and more extensive than anyone North or South had expected, and on July 22, 1861, Congress authorized a volunteer army of 500,000 men.
Those named for states usually referred to Southern states that had been occupied.
It was more common to name departments for rivers (such as Department of the Tennessee, Department of the Cumberland) or regions (Department of the Pacific, Department of New England, Department of the East, Department of the West, Middle Department).
Military Divisions were similar to the more modern term Theater; and were modeled close to, though not synonymous with, the existing theaters of war.
An organization that covered a defined region, including responsibilities for the Federal installations therein and for the field armies within their borders.
It is a misconception that the South held an advantage because of the large percentage of professional officers who resigned to join the Confederate army.
At the start of the war, there were 824 graduates of the U. Military Academy on the active list; of these, 296 resigned or were dismissed, and 184 of those became Confederate officers.
The Union Army fought and eventually defeated the Confederate Army during the war.