This is the site of the two major Civil War battles. The first began on July 16, 1861 when Union General Irvin McDowell, who was in charge of all troops in and around Washington, D.C., took his army of 35,000 soldiers on a campaign from D.C. to capture Richmond, VA and "end the war". Although most of the 35,000 were new recruits, everyone in Washington presumed an easy victory. So much so that many citizens and politicians followed behind the advancing army to watch and enjoy the victory.
The Union Army encountered the Confederates on July 18th at Bull Run, near Manassas, where 22,000 opposing soldiers were encamped. McDowell spent two days scouting the enemy and devising his strategy before attacking. The two days of delay gave the Confederates time to receive 10,000 additional support troops. After a fierce battle, where 460 Union and 387 Confederate soldiers were killed, the Union advance was repelled. The Union army retreated back towards Washington, where they physically ran into all the citizens and politicians who had been trailing. Chaos ensued, and it became a great victory for the Confederates.
Eight months later, Union General George McClellan took command of union forces in Washington and began another mission to Richmond, where he engaged the enemy. After several battles in which neither side could claim victory, McClellan began withdrawing his forces back towards Washington.
With several famous Confederate Soldiers involved, such as Robert E. Lee and Stonewall Jackson, a major battle erupted at Manassas again. The battle raged for two days, with the Confederates once again repulsing the Union Army, sending them retreating under darkness back to Washington. There were reports of casualties numbering around 10,000 for the Union forces and 8,300 for the Confederates.