The Battle of Thoroughfare Gap, also known as Chapman's Mill, took place on August 28, 1862, in Fauquier County and Prince William County, Virginia, as part of the Northern Virginia Campaign of the American Civil War. Confederate forces under Maj. Gen. James Longstreet successfully drove back Union forces under Brig. Gen. James B. Ricketts and Col. Percy Wyndham, allowing his corps to unite with that of Thomas J. "Stonewall" Jackson prior to the Second Battle of Bull Run (Second Manassas). Background On August 26, Maj. Gen. Stonewall Jackson led his corps of the Army of Northern Virginia through Thoroughfare Gap, on his way to raiding the Union supply depot at the Manassas Junction. In response to the raid, the following day Union Maj. Gen. Irwin McDowell set out from Warrenton to Manassas Junction to engage Jackson. In order to protect his army's left flank, he dispatched Brig. Gen. James B. Ricketts's brigade and the 1st New Jersey Cavalry under Sir Percy Wyndham towards the Gap. Ricketts stopped at Gainesville, to the east, while Wyndham occupied the gap. Maj. Gen. James Longstreet's corps, meanwhile, followed in the path of Jackson's march and was approaching the gap from the west late on the evening of August 27. Battle At 9:30 a.m. on August 28, Wyndham's troopers encountered Longstreet's vanguard while attempting to fell trees across the road on the east side of the gap. Wyndham immediately dispatched a courier to Ricketts at Gainesville. Ricketts's advance was slow, however, and he had only reached Haymarket, to the east, by 2 p.m. By that point, Wyndham had been driven from the Gap and Longstreet took possession of it. The Federal position was still strong though, as a series of low-lying ridges east of the gap provided an excellent ground for defending the road to Gainesville, and the Confederates had not occupied the hills to the north and south of the gap. In order to meet this Union threat, Longstreet developed a plan, whereby he would command the gap from the high ground on either side and then outflank the Union position on the eastern ridge. The 9th Georgia from Col. George T. Anderson's brigade was sent to Chapman's Mill on the east side of the gap to repulse a Federal attack by the 11th Pennsylvania, who ironically, to reach the gap, had to remove the trees felled by Wyndham earlier that morning. The impediment