The Bull Run Battle, also known as the First Battle of Manassas, was a major battle of the American Civil War that took place on July 21, 1861 in Manassas, Virginia. It was the first major battle of the war and resulted in a Confederate victory. The battle was fought between the Union Army of Northeastern Virginia, led by Brigadier General Irvin McDowell, and the Confederate Army of the Potomac, led by Brigadier General P.G.T. Beauregard.