Union troops under General Irvin McDowell advanced confidently, watched by curious civilian spectators who'd ridden out from Washington expecting a quick victory. Confederate reinforcements arriving by rail helped turn the tide, and the Union retreat collapsed into a chaotic rout back toward the capital, revealing that both untrained armies, and the public, had badly underestimated the war ahead.
Washington socialites and congressmen packed picnic baskets and rode out in carriages to Centreville Ridge, treating the coming battle almost like a sporting event, confident that green Union recruits would make short work of the rebellion in a single afternoon. Instead, the day turned into a brutal education in modern warfare's confusion and cost.
The battle turned on a Confederate brigade holding firm on Henry House Hill under General Thomas J. Jackson, who earned the nickname 'Stonewall' that day for standing 'like a stone wall' against Union assaults. When fresh Confederate troops under General Joseph Johnston arrived by railroad, a novel use of rail transport for reinforcement, and struck the Union right flank, McDowell's exhausted men broke.
The retreat became a genuine panic, soldiers and fleeing spectators tangled together on the road back to Washington, abandoning wagons, weapons, and dignity alike. Confederate forces were too disorganized themselves to pursue effectively, but the psychological impact was seismic: both sides now understood this would be a long, grinding war, not a summer's adventure.
Key people: Irvin McDowell, Thomas J. Jackson, Joseph Johnston