During July and August, Gen. Robert E. Lee, with Richmond secure after his victorious Seven Days' Campaign, shifted operations to north-central Virginia, shuttling his army in stages northwestward against the newly created Union Army of Virginia under Maj. Gen. John Pope. During the last week of August, Lee decided on a bold gamble against Pope, whose 75,000 men were located on the north side of the Rappahannock River.
Lee, in what became a pattern of his brilliant generalship, split his army. On August 25, Maj. Gen Thomas J. "Stonewall" Jackson, with half the army, began a wide flanking marcharound Pope's right to sever his communication and supply lines. In one of the war's greatest marches, Jackson's rugged Foot Cavalry covered 50 miles, falling on the huge Union supply depot at Manassas Junction. While Jackson's hungry, footsore veterans burned and feasted on the 27, Pope abandoned his position, fanning his units northward. Lee, with Maj. Gen. James Longstreet's corps, also left the Rappahannock, arcing northward to join Jackson.
The elusive Jackson left the smoldering depot during the night, marching to a wooded ridge north of the Warrenton Pike on the old Bull Run battlefield. throughout the 28th, the Federals, marching and countermarching, under confusing and contradictory orders, searched for the Confederates. At sunset, Brig. Gen. John Gibbon's brigade, marching on the Warrenton Pike, crossed Jacksons' concealed front. The general seized the opportunity and attacked. In this Battle of Groveton, the 2 foes fought fiercely until dark.
pope ordered a concentration against Jackson, neglecting Longstreet, who had entered Thoroughfare Gap to the west during the evening of the 28th. As Union divisions- some of which belonged to Maj. Gen. George B. McClellan's Army of the Potomac- reached the field on the 29th, Pope hurled them by detail against Jackson's veterans, located behind an abandoned railroad embankment. The Confederates repulsed 6 bloody assaults by the right half of the Union army. On Pope's left, Maj. Gen. Fitz John Porter failed to attack Jackson's flank, arguing that he could not because of Longstreet's arrival.
During the night, Lee pulled back some units to buttress his lines. Pope misinterpreted the Confederate retrenchment as a retreat, and on the 30th, he advanced to cut it off. Jackson's men were waiting and once more battered the charging Union troops. Finally, Lee sent Longstreet's 30,000 men forward in a furious counterattack. The entire Union line crumbled under the assault, withdrawing a mile before a stubborn rear guard halted the Confederates.
Pope regrouped his defeated army on the heights near Centreville on the 31st. Two corps from McClellan's command arrived, belatedly, to bolster Pope's ranks. Meanwhile, Lee sought another opportunity to turn the Union right, ordering Jackson to a position west of Chantilly. The next day, Jackson advanced, which resulted in the Battle of Chantilly. Pope withdrew closer to Washington, D.C., and the campaign ended.
Recriminations followed this humiliating defeat. The boastful pope, thoroughly outgeneraled by Lee and Jackson, blamed McClellan and his clique of officers for not reinforcing him promptly and adequately. As for the late arrival of McClellan's corps and his egotistical criticism of Pope, President Lincoln considered McClellan's evident lack of cooperation unpardonable. some cabinent members thought he should be court-martialed. Lincoln knew that only yhe popular McClellan could reorganize the demoralized army, and the general resumed command as Lee marched northward into Maryland.
***Jackson with a force of 24,000 men marched northwest out of Richmond on 13 July to strike advance elements of Pope's army. He met and defeated the Federal II Corps, Banks commanding, at Cedar Mountain on 9 August, but did not pursue because Pope's main body was nearby. Lee followed Jackson out of Richmond with the remainder of the Army of Northern Virginia, intending to outflank and cut off Pope before he and McClellan could join forces.
Lee conducted a series of feints and maneuvers which caused Pope to withdraw to the northern bank of the Rappahannock. 0n 25 August Lee sent Jackson, followed the next day by Longstreet's divisions, on a wide turning movement around the Federal right flank.
Jackson came in behind Pope on 26 August at Manassas, where he destroyed Federal military stores. Pope immediately moved northeast and clashed with Jackson at Groveton on 28 August. Jackson then took up a defensive position in the general vicinity of the Battle of Bull Run. On 29 August, as McClellan's troops began to arrive on the scene, Pope moved to crush Jackson. A 2-day engagement ensued, during which Longstreet's divisions arrived and turned the tide against the Federals. Pope retired to Washington, fighting off an enveloping Confederate force at Chantilly on the way.
This brought to a close the Manassas Campaign, or Second Bull Run. For the Confederates it was the second Manassas Campaign. During the period 48,527 Confederates had engaged 75,696 Federals; the Confederates had lost 1,481 killed, 7,627 wounded, and 89 missing; and the Federals 1,724 killed, 8,372 wounded, and 5,958 missing. Following the campaign Halleck dissolved the Army of Virginia and gave McClellan the command of all forces around the capital. Pope was sent to a command in Minnesota.