When, on Apr. 12, 1861, the Confederate commander P. G. T. Beauregard, acting on instructions, ordered the firing on Fort Sumter, hostilities officially began. Lincoln immediately called for troops to be used against the seven seceding states, which were soon joined by Arkansas, North Carolina, Virginia, and Tennessee, completing the 11-state Confederacy. In the first important military campaign of the war untrained Union troops under Irvin McDowell, advancing on Richmond, now the Confederate capital, were routed by equally inexperienced Confederate soldiers led by Beauregard and Joseph E. Johnston in the first battle of Bull Run (July 21, 1861). This fiasco led Lincoln to bring up George B. McClellan (1826–85), fresh from his successes in W Virginia (admitted as the new state of West Virginia in 1863).
After the retirement of Winfield Scott in Nov., 1861, McClellan was for a few months the chief Northern commander. The able organizer of the Army of the Potomac, he nevertheless failed in the Peninsular campaign (Apr.–July, 1862), in which Robert E. Lee succeeded the wounded Johnston as commander of the Confederate Army of Northern Virginia. Lee planned the diversion in the Shenandoah Valley, which, brilliantly executed by Thomas J. (Stonewall) Jackson, worked perfectly. Next to Lee himself Jackson, with his famous "foot cavalry," was the South's greatest general.
Lee then went on to save Richmond in the Seven Days battles (June 26–July 2) and was victorious in the second battle of Bull Run (Aug. 29–30), thoroughly trouncing John Pope. However, he also failed in his first invasion of enemy territory. In September, McClellan, whom Lincoln had restored to command of the defenses of Washington, checked Lee in Maryland (see Antietam campaign). When McClellan failed to attack the Confederates as they retreated, Lincoln removed him again, this time permanently.
Two subsequent Union advances on Richmond, the first led by Ambrose E. Burnside (see Fredericksburg, battle of) and the second by Joseph Hooker (see Chancellorsville, battle of), ended in resounding defeats (Dec. 13, 1862, and May 2–4, 1863). Although Lee lost Jackson at Chancellorsville, the victory prompted him to try another invasion of the North. With his lieutenants Richard S. Ewell, James Longstreet, A. P. Hill, and J. E. B. (Jeb) Stuart, he moved via the Shenandoah Valley into S Pennsylvania. There the Army of the Potomac, under still another new chief, George G. Meade, rallied to stop him again in the greatest battle (July 1–3, 1863) of the war (see Gettysburg campaign).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.