First Major Battle of American Civil War at Bull Run
In the early months of the American Civil War, both the Union and Confederacy mobilized large volunteer armies with expectations of a quick resolution, as Union forces under Brigadier General Irvin McDowell advanced toward Richmond, Virginia, to end the rebellion swiftly. Confederate troops commanded by Brigadier General P.G.T. Beauregard positioned themselves near Manassas Junction to block the Union advance, with reinforcements from the Shenandoah Valley under Joseph E. Johnston arriving by rail. On July 21, 1861, the opposing armies clashed in the First Battle of Bull Run near Manassas, Virginia, in fighting that involved approximately 35,000 Union and 20,000 Confederate troops across a day of confused engagements around key hills and streams. The battle saw initial Union success give way to Confederate counterattacks, including the famous stand of Thomas J. Jackson's brigade, leading to a disorganized Union retreat toward Washington, D.C. Casualties totaled around 3,000 for the Union and 2,000 for the Confederacy, shattering illusions of a short war.
Why it matters: The Confederate victory boosted Southern morale and demonstrated that the conflict would be prolonged and bloody, prompting both sides to expand their armies and prepare for extended warfare that ultimately lasted four years. It also highlighted logistical challenges like railroad use that would define later campaigns.