In the East, most of the war’s fighting took place in a narrow corridor between Washington and Richmond—a distance of only 100 miles—as a succession of Union generals led the Army of the Potomac (as the main northern force in the East was called) toward the Confederate capital, only to be turned back by southern forces. The first significant engagement, the first Battle of Bull Run, took place in northern Virginia on July 21, 1861. It ended with the chaotic retreat of the Union soldiers, along with the sightseers and politicians who had come to watch the battle. Almost 800 men died at Bull Run, a toll eclipsed many times in the years to come, but more Americans than had been killed in any previous battle in the nation’s history. The encounter disabused both sides of the idea that the war would be a brief lark.
During the first two years of the war, most of the fighting took place in Virginia and Maryland.
In the wake of Bull Run, George B. McClellan, an army engineer who had recently won a minor engagement with Confederate troops in western Virginia, assumed command of the Union’s Army of the Potomac. A brilliant organizer, McClellan succeeded in welding his men into a superb fighting force. He seemed reluctant, however, to commit them to battle, since he tended to overestimate the size of enemy forces. And as a Democrat, he hoped that compromise might end the war without large-scale loss of life or a weakening of slavery. Months of military inactivity followed.