July 21, 1861 in Prince William County, Virginia, just north of the city of Manassas and about 25 miles west-southwest of Washington, D.C. the first major battle of the civil war took place,the battle of bull run.
the Northern public clamored for a march against the Confederate capital of Richmond, Virginia, which could bring an early end to the war.
Yielding to this political pressure, unseasoned Union Army troops under Brig. Gen. Irvin McDowell advanced across Bull Run against the equally unseasoned Confederate Army under Brig. Gen. P.G.T. Beauregard near Manassas Junction.
Like this but on a much larger scale with more people
The union was shocked and mortified when the south won. the union thought it would be simple but the south's knowledge of the terrain and skill with guns eventually won.