What were the effects of the battle on both sides? In The first battle of bull run story On July 21, 1861 the First Battle of Bull Run occurred. It was the first real major conflict of the American Civil War. A Union army, consisting of 28,000 men, commanded by General McDowell, fought 33,000 Confederates under General Beauregard. The Union army, under pressure to crush the rebellion in the South, marched towards Richmond, but met the Confederate forces coming north from Manassas, a Southern base. At the beginning of the five hour battle the Union soldiers had the Confederates on the retreat, except for one brigade commanded by General Jackson. Due to Jackson's ability to hold his ground and his stubbornness, the men saw him similar to a stone wall, hence the nickname "Stonewall" Jackson. Thanks to Jackson the Confederates were able to hold out until General Johnston showed up with 9000 reinforcements to help out Beauregard near Henry House Hill. The arrival changed the course of the battle and soon the Union soldiers were fleeing back to Washington. However, because of the disorganization of Beauregard's army, they could not pursue McDowell any further. The battle proved that this was not going to be a one sided war for either side, as was predicted. The casualties soared to 2,900 killed, wounded, captured, or missing for McDowell's army and 2,000 for Beauregard's. The battle spurred a sense of victory in the South, pushing them on, and in the North a feeling for revenge.