On 29 August 1862 Stonewall Jackson's Confederate Corps of the Army of Northern Virginia would be sorely tested along the Unfinished Railroad at the Second Battle of Manassas.
Stonewall Jackson (CSA) John Pope (USA) Fitz-John Porter (USA)
Jackson had succeeded in picking a fight with Union General John Pope and his Army of Virginia, and now the force twice his size closed in on him for the kill. Throughout the day of 29 August, Union forces would hammer Jackson's Corps.
As it happened Pope's attacks ended up piece-meal affairs, poorly supported, and never ultimately successful in breaking Jackson's line. This was, in part, owing to a serious miscommunication with the Army commander and the commander of the Union V Corps detached from the Army of the Potomac, US General Fitz-John Porter.
Porter's Union V Corps was, the mind of the US General John Pope, supposed to march down the Manassas-Gainesville Rd (modern Wellington Rd) to turn the right flank of Jackson's Corps and cut off his retreat towards Thoroughfare Gap. The problem was that Pope never made the crucial aspect of this movement clear to his subordinate and, indeed, his written orders stressed a need to guard against becoming isolated from lines of retreat back to Centreville. Hence, Porter, on 29 August 1862, proceeded with caution towards Gainesville and Jackson's flank. When he ran into the Confederate Cavalry of J.E.B. Stuart, horsemen who dragged branches to kick up dust and feign great numbers, Porter halted. His fear of a massive force at his front would soon be realized as Longstreet's Corps did, in fact, move into place on Stonewall Jackson's flank that afternoon. There was to be no flank attack. Indeed, Robert E. Lee's army was reunited, and Pope was in serious trouble.
Map of the situation at midday on 29 August 1862. Porter is stalled, Longstreet now in position next to Jackson, and Pope focused totally on Jackson. [Map by Hal Jespersen, www.cwmaps.com]
Meanwhile, US General John Pope oversaw a series of "diversionary" attacks on Jackson's line as he waited for Porter's V Corps to deliver the knock-out blow. The multiple attacks, some of which gained initial success, all ended failures owing to lack of support and coordination.
Still, that evening, despite a stiff clash involving Longstreet's Corps, John Pope was confident of victory the next day.
You can visit the ground at Manassas National Battlefield Park along the Unfinished Railroad -- but do beware of ticks on the warmer months in that area: http://www.nps.gov/mana/index.htm
This site has a wealth of information on the battle: http://www.civilwar.org/battlefields/second-manassas.html
Here is the NPS account of the battle: http://www.cr.nps.gov/hps/abpp/battles/va026.htm