The First Battle of Bull Run, referred to as the First Battle of Manassas in the South, (July 21, 1861) was the first major land battle of the American Civil War. (The difference in the two names results from the difference in naming conventions used by each side in the war. Confederates named battles for the nearest town or city; the Union named battles for the nearest river or body of water.)

Brigadier General Irvin McDowell was appointed to command the Army of Northeastern Virginia, by President Abraham Lincoln. He was prodded to attack by the Washington politicians, who wanted a quick victory to solidify their standing. McDowell did not want to attack, stating that his forces were green, but eventually was forced to.

McDowell's plan was to use Brig. Gen. Daniel Tyler's division to feint an attack on Stone Bridge, which went across Bull Run, while Colonel Thomas A. Davies's brigade would feint at Blackburn's Ford. Under cover of these feigning maneuvers, the main attack would be by Brig. Gens. David Hunter and Samuel P. Heintzelman, on the Confederate troop's left flank (the Union's right). This was a sound plan; however, McDowell's forces were much too green to carry it out effectively.

On the other hand, the Confederate troops were also in disorder. Commanded overall by Brig. Gen. P.G.T. Beauregard (the hero of Fort Sumter), their order of battle was rather unwieldy, with about 1/3 of their troops still marching from the Shenandoah Valley. Only a small brigade under Colonel Nathan Evans stood in the path of the Union Army. Had this unit faltered, or not been present, the flank attack would have succeeded. Ultimately these few men were unable to hold their positions after the entire Federal army attacked. The Confederate units retreated.

However, a group of Virginia soldiers commanded by Brig. Gen. Thomas J. Jackson, refused to lose ground. Fellow Confederate officer Brig. Gen. Barnard Bee then famously shouted the following order: "Look! There is Jackson standing like a stone wall! Rally behind the Virginians!" The Confederates did just that, and the battle resulted in a humiliating rout of Union forces and a disorderly retreat, bringing the battle to a halt. Because of Bee's command, and the subsequent victory, General Jackson became known as "Stonewall Jackson."

General Jackson's arrival meant that the Army of the Shenandoah, under Brig. Gen. Joseph Johnston had arrived, and this force, along with Beauregard's Army of the Potomac, attacked. The Federal right flank, which was in disorder because of the halted attack, was routed and driven back. By the end of the day these units were in full flight.

The elite of nearby Washington, DC, expecting an easy Union victory, had come out to watch the battle and picnic. When the Union Army was driven back, the roads back to Washington were blocked by panicked civilians attempting to flee in their carriages. Further confusion ensued when an artillery shell fell on a carriage blocking the main road north. Although the Confederates would probably have won the war had they marched on Washington during the rout, they were too exhausted to follow through with a pursuit of the enemy.

Casualties totaled approximately 3,000 - 5,000 Union troops and 2,000 Confederates.

See also

• Second Battle of Bull Run