Note: This is also known as the First Battle of Manassas, Bull Run is the name of the river next to Manassas.
The Union army was destroyed by the Confederate army in the first major battle of the U.S. Civil War (July 21, 1861). The North realized the war could not be won as easily as they initially thought.
Two months before, the war had begun as the Confederate army captured Fort Sumter in South Carolina. General in Chief Winfield Scott proposed a plan to subdue the Southern states. Dubbed the "Anaconda Plan", it had the U.S. Navy block imports to the South along the Atlantic coast and along the Gulf of Mexico. It later wanted to split the South up by going through the Mississippi River.
That plan was very passive. Many people thought a more aggressive approach was necessary, and they believed that capturing the Confederate capital of Richmond would quickly end the war. Irwin McDowell was selected as the field commander that would lead the troops in battle. Winfield Scott was 75 years old and couldn't lead an army.
McDowell formed an army, the Army of Northeastern Virginia, in order to take on the the Confederates. However, they were in a rush, and the soldiers were unexperienced and were not trained. However, Lincoln insisted that he campaign, despite McDowell's plea.
Unbeknownst to the Union Army, there was a spy within Washington feeding the Confederates information. Rose Greenhow, a prominent DC Socialite, was providing Confederate general Thomas Jordan with critical information about Union strategies. So, going into this battle, Confederates were one step ahead of the Union troops.
On July 16, 1861, McDowell left Washington with 35,000 men. He had hoped to reach Centreville by July 17, but his army was unaccustomed to marching, so they often broke ranks to wander off to pick apples or berries or get water. After two days (instead of one), they arrived, and they were allowed to rest in Centreville.
Joseph Johnston and his Confederate forces began heading to Manassas Junction (their destination), so McDowell would be faced with 34,000 troops instead of 22,000.
The Sides of the Battle
The Union army was made up of McDowell's Army of Northeastern Virginia, which included 5 divisions.
The Confederate army was made up of two armies
The Confederate Army of the Potomac
This was headed by Brigadier General P.G.T. Beauregard, and this was composed of 22,000 men.
The Confederate Army of the Shenandoah
This was led by Brigadier General Joseph Johnston, and this was made of 12,000 men.
In the morning, the Union army was winning. They collapsed the Confederate's line at 11:30 am, forcing them to retreat up Henry House Hill, with the help of William T. Sherman and other generals. Onlookers watching from Washington prematurely celebrated a Union victory.
Later, Confederate troops started bringing more and more reinforcements. First, Brig. Gen Thomas Jackson came to help disorganized Confederates, accompanied by Col. Wade Hampton, and Col. J.E.B. Stuart's cavalry. The Confederates occupied Henry House, which housed 85-year-old Judith Carter Henry. She refused to leave the house and was killed by a union cannon.
Confederate Brig. Gen. Barnard Bee tried to inspire his men to get in formation by shouting "There is Jackson standing like a stone wall." That created Thomas Jackson's nickname- "Stonewall" Jackson. After that, the Confederates began advancing, and they were mistaken for Union troops, so they were able to penetrate their defense and capture their guns. P.G.T Beauregard ordered his troops forward, and Union soldiers began leaving by the masses. McDowell rode around trying to corral everyone back to the battlefield, but many people had had enough. McDowell's forces crumbled, and they had to retreat.
The Confederate troops were too disorganized to capitalize on their advantage and pursue the Union troops.
Northerners expected an easy victory, and the loss gave them a reality check. The southerners rejoiced and it gave them a lot of hope. Lincoln removed McDowell from command and replaced him with George McClellan, who created the Army of the Potomac (not to be confused with the Confederate army of the same name) that would protect Washington and the surrounding areas. Overall, this was a portentous battle that signaled that the Civil War would be long and gruesome.