General Irvin McDowell felt confident that victory was at hand. The Federal flanking column had marched around and behind the Confederate defenses along Bull Run. Nearly 18,000 troops were at, or en route, to the front. Confederate resistance on Matthews Hill had collapsed. After a two-hour delay to reorganize his available men, the Union commander turned his attention to pressing the retreating foe and occupying Henry Hill.
McDowell directed two artillery batteries, eleven guns total, to occupy this high ground. The battery command protested the lack of infantry support would make their cannon vulnerable to capture. The order stood. No sooner had the Federal artillery unlimbered when Confederate batteries opened fire from 300 yards away. Over the next hour, the opposing batteries dueled across the field. Suddenly from the far woods came a blood-chilling cry -- the revel yell. Through dense smoke, Confederate infantry swarmed across the field.
Source: U.S. Department of the Interior, National Park Service