(Wikipedia) The Second Battle of Bull Run or Second Manassas was fought August 28–30, 1862,[1] as part of the American Civil War. It was the culmination of an offensive campaign waged by Confederate Gen. Robert E. Lee's Army of Northern Virginia against Union Maj. Gen. John Pope's Army of Virginia, and a battle of much larger scale and numbers than the First Battle of Bull Run (First Manassas) fought in 1861 on the same ground.
Following a wide-ranging flanking march, Confederate Maj. Gen. Thomas J. "Stonewall" Jackson captured the Union supply depot at Manassas Junction, threatening Pope's line of communications with Washington, D.C. Withdrawing a few miles to the northwest, Jackson took up defensive positions on Stony Ridge. On August 28, 1862, Jackson attacked a Union column just east of Gainesville, at Brawner's Farm, resulting in a stalemate. On that same day, the wing of Lee's army commanded by Maj. Gen. James Longstreet broke through light Union resistance in the Battle of Thoroughfare Gap and approached the battlefield.
Pope became convinced that he had trapped Jackson and concentrated the bulk of his army against him. Continued