When McDowell advanced upon the Confederate forces under Beauregard at Manassas, Johnston moved from the Shenandoah Valley with great rapidity to Beauregard's assistance.
As senior officer he took command on the field, and at Bull Run (Manassas) (q.v.) won the first important Confederate victory.
McClellan and the Army of the Potomac faced Johnston, who with the Army of northern Virginia lay at Manassas, exercising and training his men with no less care than his opponent.
By the ist of September the campaign of "Second Manassas" was over.
Of the six great impacts made upon the Confederacy, four were upon Virginian soil: the first Manassas campaign (1861), the Peninsular battles (1862), second Manassas (1862), Fredericksburg, Chancellorsville (1862-63) and the great Wilderness-Petersburg series of attacks (1864-65).