Answer:
The First Battle of Bull Run was a clash between Union and Confederate forces in Virginia on July 21, 1861. It was the first major battle of the Civil War. The cause of the fighting was the Union's attack on the city of Richmond, near the battlefield, which served as the capital of the Confederacy.
Each party forces consisted mainly of poorly trained volunteer soldiers. The Union was winning for a long time during the battle, but the advance of the troops stopped on a hill called Henry House Hill. At Henry House Hill, Confederate forces received reinforcements, with the help of which Confederate Commander P. G. T. Beauregard carried out a counterattack. In counterattack, Confederate forces managed to break the Union’s line of defense, leading Union soldiers to panic and uncontrollable withdrawal toward Washington.