The first battle of Bull Run is considered the first major battle of the American Civil War. It occurred on July 21, 1861 and was fought near the Manassas railroad junction in the state of Virginia. This battle was named by the Union army after a stream that ran through the battlefield that was called Bull Run. For the Confederate army, the first battle of Bull Run would become known as the first battle of Manassas.
For this first battle, the Union army was led by Brigadier General Irvin McDowell and consisted of about 30,000 men. It was divided into four different divisions with each part led by its own commander. The Confederate army was less structured and consisted of two different armies composed of 13 different brigades. Brigadier General Pierre G. T. Beauregard led the first army, the Army of the Potomac, and Brigadier General Joseph E. Johnston led the second, the Army of Shenandoah. With these two armies combined, however, the sides of north and south were almost equal in number.
The initial plan by both leaders for this battle was to make the other side think that a right flank attack was planned. Instead, they were actually organizing a major attack toward their left. Had this been a successful move by both parties and occurred at the exact same time, each army would have merely missed the other, thereby putting the Union and Confederate armies behind each other.
This did not, however, turn out the be the case at the first battle of Bull Run — although the Union army appeared more organized, in reality, McDowell had no actual experience in planning military strategy. He had also been given troops that had no true military training. The other side was equally unprepared, but time was on the Confederate side since McDowell’s flanking attack began two and a half hours behind schedule.
Although Beauregard was not any more prepared for battle than McDowell, reports that a larger number of men were attacking his left flank, along with a Union army that was not fully engaging on his right, gave Beauregard insight as to what McDowell was planning. He began moving his troops to the left to counter McDowell’s main point of attack. This move could have proved disastrous for Beauregard since McDowell had more than 18,000 men converging on that side, but one of the smaller brigades led by Colonel "Shank" Evans was able to block them at a spot called Matthew’s Hill.
Even with Evans' help and the assistance of the other brigades that had shifted from their positions when they heard the fighting, the Confederates were still badly outnumbered. They were eventually forced to pull back and make their way to Henry House Hill. The Union troops' ineptness made them slow to respond to this movement and by the time they were able to follow, another southern brigade had made it there to assist in their defense.
Despite the additional Confederate soldiers, McDowell still ordered his two artillery batteries to advance. In the end, Beauregard had enough troops in place to form his own advance and the Union army had no choice but to retreat. With McDowell’s troops retreating and the Confederate soldiers in no shape to go after them, the first battle of Bull Run was over.