The first major land battle of the American Civil War dispelled expectations of a short conflict and exposed deep military deficiencies on both sides.
Key Facts
- Date
- July 21, 1861
- Location
- Prince William County, Virginia
- Troops engaged per side
- ~18,000 troops
- Union total force available
- 35,000 troops
- Confederate total force available
- ~32,000 troops
- Distance from Washington D.C.
- ~30 miles
By the Numbers
Location
Cause → Event → Consequence
Following the Confederate attack on Fort Sumter, Northern public opinion and political pressure demanded an aggressive advance toward the Confederate capital at Richmond, Virginia. Brigadier General Irvin McDowell was ordered to move his inexperienced Union army against Confederate forces camped near Manassas Junction under Brigadier General P. G. T. Beauregard, despite the poor training of both armies.
On July 21, 1861, McDowell launched a flank attack that initially threatened the Confederate left, but the plan was poorly executed. Confederate reinforcements under Brigadier General Joseph E. Johnston arrived by rail from the Shenandoah Valley. A Virginia brigade under Thomas J. Jackson held firm, earning him the nickname 'Stonewall.' The Confederates then launched a strong counterattack, routing the Union forces.
The Union retreat collapsed into a disorganized rout toward Washington, D.C. Both sides recognized the war would be far longer and costlier than anticipated. The battle exposed critical tactical failures common to the war's early phase, including piecemeal troop commitments, frontal assaults, poor intelligence, and ineffective command, prompting both governments to build more professional armies.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Irvin McDowell.
Side B
1 belligerent
P. G. T. Beauregard, Joseph E. Johnston, Thomas J. Jackson.