Fairfax County and Prince William County , Virginia
This was the first major land battle of the armies in Virginia. On July 16, 1861, the untried Union army under Brig. Gen. Irvin McDowell marched from Washington against the Confederate army, which was drawn up behind Bull Run beyond Centreville. On the 21st, McDowell crossed at Sudley Ford and attacked the Confederate left flank on Matthews Hill. Fighting raged throughout the day as Confederate forces were driven back to Henry Hill. Late in the afternoon, Confederate reinforcements extended and broke the Union right flank. The Federal retreat rapidly deteriorated into a rout. Thomas J. Jackson earned the nom de guerre “Stonewall.” By July 22, the shattered Union army reached the safety of Washington.