Battle of Chantilly The Battle of Chantilly ( or Ox Hill , the Confederate name ) took place on September 1 , 1862 , in Fairfax County , Virginia , as the concluding battle of the Northern Virginia Campaign of the American Civil War . Thomas J . " Stonewall " Jackson ' s corps of the Army of Northern Virginia attempted to cut off the line of retreat of the Union Army of Virginia but was attacked by two Union divisions . During the ensuing battle , both Union division commanders were killed but the Union attack halted Jackson ' s advance . Background . Defeated in the Second Battle of Bull Run on August 30 , Union Maj . Gen . John Pope ordered his Army of Virginia to retreat to Centreville . The movement began after dark , with Maj . Gen . Irvin McDowell ' s III Corps providing cover . The army crossed Bull Run and the last troops across , Maj . Gen . Franz Sigel ' s I Corps , destroyed Stone Bridge behind them . Gen . Robert E . Lee decided not to press the advantage gained that day , largely because he knew his Army of Northern Virginia was exhausted from two weeks of nearly constant marching and nearly three days of battle , so the Union retreat went unmolested . Lee ' s decision also allowed the Army of Virginia ' s II Corps , under Maj . Gen . Nathaniel P . Banks , to consolidate with the bulk of Pope ' s army , marching in from Bristoe Station , where they had been guarding the army ' s trains . More importantly , Lee ' s decision bought time for the Union to push to the front the Army of the Potomac ' s II , V , and VI Corps , which had been brought from the Peninsula and — much to Maj . Gen . George B . McClellan ' s dismay — placed under Pope ' s command . By the morning of August 31 , Pope began to lose his grasp on command of his army . The defeat at Second Bull Run seemed to have shattered his nerve and Pope was unsure what to do next ; he knew Washington wanted an attack but he feared Lee might strike first and destroy his reforming force before it was ready to fight again . Calling a conference of his corps commanders — something he had been loath to do previously in the Virginia Campaign — in his Centreville headquarters , Pope agreed with their decision to retreat further into the Washington defenses . But a message from General - in - Chief Henry W . Halleck directed him to attack and he ordered an advance on Lee ' s forces on the Manassas field . Lee , however , had already set in motion his own plan that would rob Pope of the initiative to attack . Lee directed Maj . Gen . Thomas J . " Stonewall " Jackson to march his troops around Pope ' s right flank to get behind the Union position at Centreville . Leading the way and scouting for any Union blocking force was Confederate cavalry under the command of Maj . Gen . J . E . B . Stuart . Maj . Gen . James Longstreet ' s command would remain in place for the day to deceive Pope into believing that Lee ' s entire force remained in his front , while Jackson ' s command made their flanking march , north and then east , to take strategically important Germantown , Virginia , where Pope ' s only two routes to Washington — the Warrenton Pike ( modern U . S . Route 29 ) and the Little River Turnpike ( modern U . S . Route 50 ) — converged . Jackson ' s men , hungry and worn , moved slowly and bivouacked for the night at Pleasant Valley , three miles northeast of Centreville . As Pope settled down for the night on August 31 , he was unaware that Lee was on the verge of turning his flank . During the night two events occurred that would force Pope to change his mind . A staff officer arrived from the Germantown position to report that a heavy force of cavalry had shelled the intersection before retreating . Fortunately for Lee and Stuart , Pope dismissed the cavalry as little more than a patrol . But when , hours later , two Union cavalrymen reported seeing a large mass of infantry marching east down the Little River Turnpike , Pope realized that his army was in danger . He countermanded actions preparing for an attack and directed the army to retreat from Centreville to Washington ; he also sent out a series of infantry probes up the roads that Lee might use to reach his troops as they pulled back . Battle . On the morning of September 1 , Pope ordered Maj . Gen . Edwin V . Sumner of the II Corps , Army of the Potomac , to send a brigade north to reconnoiter ; the army ' s cavalry was too exhausted for the mission . But at the same time , he continued his movement in the direction of Washington , sending McDowell ' s corps to Germantown ( on the western border of modern day Fairfax , Virginia ) , where it could protect an important intersection the army needed for the retreat . He also sent two brigades from Maj . Gen . Jesse L . Reno ' s IX Corps , under the command of Brig . Gen . Isaac Stevens , to block Jackson . Maj . Gen . Philip Kearny ' s division from the III Corps followed later that afternoon . Jackson resumed his march to the south , but his troops were tired and hungry and made poor progress as the rain continued . They marched only three miles and occupied Ox Hill , southeast of Chantilly Plantation , and halted , while Jackson himself took a nap . All during the morning , Confederate cavalry skirmished with Union infantry and cavalry . At about 3 p . m . , Steven ' s division arrived at Ox Hill . Despite being outnumbered , Stevens chose to attack across a grassy field against Brig . Gen . Alexander Lawton ' s division in the Confederate center . The Union attack was initially successful , routing the brigade of Colonel Henry Strong and driving in the flank of Captain William Brown , with Brown killed during the fighting . The Union division was driven back following a counterattack by Brig . Gen . Jubal Early ' s brigade . Stevens was killed during this attack about 5 p . m . by a shot through his temple . A severe thunderstorm erupted about this time , resulting in limited visibility and an increased dependence on the bayonet , as the rain soaked the ammunition of the infantry and made it useless . Kearny arrived about this time with his division and deployed Brig . Gen . David B . Birney ' s brigade on Stevens ' s left , ordering it to attack across the field . Birney managed to maneuver close to the Confederate line but his attack stalled in hand - to - hand combat with Maj . Gen . A . P . Hill ' s division . Kearny mistakenly rode into the Confederate lines during the battle and was killed . As Kearny ' s other two brigades arrived on the field , Birney used the reinforcements as a rear guard as he withdrew the remainder of the Union force to the southern side of the farm fields , ending the battle . Aftermath . That night , Longstreet arrived to relieve Jackson ' s troops and to renew the battle in the morning . The lines were so close that some soldiers accidentally stumbled into the camps of the opposing army . The Union army withdrew to Germantown and Fairfax Court House that night , followed over the next few days by retreating to the defenses of Washington . The Confederate cavalry would attempt a pursuit but failed to cause significant damage to the Union army . The fighting was tactically inconclusive . Although Jackson ' s turning movement was foiled and he was unable to block the Union retreat or destroy Pope ' s army , National Park Service historians count Chantilly as a strategic Confederate victory because it neutralized any threat from Pope ' s army and cleared the way for Lee to begin his Maryland Campaign . The Confederates claimed a tactical victory as well because they held the field after the battle . Two Union generals were killed , while one Confederate brigade commander was killed . Pope , recognizing the attack as an indication of continued danger to his army , continued his retreat to the fortifications around Washington , D . C . Lee began the Maryland Campaign , which culminated in the Battle of Antietam , after Pope retreated out of Virginia . The Army of the Potomac , under Maj . Gen . George B . McClellan , absorbed the forces of Pope ' s Army of Virginia , which was disbanded as a separate army . Battlefield today . The site of the battle , once rural farmland , is now surrounded by suburban development in Fairfax County . The modern thoroughfares of 50 ( Lee - Jackson Memorial Highway ) and State Route 286 ( Fairfax County Parkway ) , as well as State Route 608 ( West Ox Road ) intersect near the location of the battle . A 4 . 8 acre ( 19 , 000 m² ) memorial park , the Ox Hill Battlefield Park , is located off of West Ox Road and lies adjacent to the Fairfax Towne Center shopping area , and includes the site of the battle . The park is under the jurisdiction of the Fairfax County Park Authority ; in January 2005 , the Authority approved a General Management Plan and Conceptual Development Plan that sets forth a detailed history and future management framework for the site . A small yard located within the nearby Fairfax Towne Center has been preserved to mark the area where Robert E . Lee and his troops marched across to get to the Ox Hill Battlefield .