Battle of Blackburn ' s Ford The Battle of Blackburn ' s Ford took place on July 18 , 1861 , in Prince William County and Fairfax County , Virginia , as part of the First Manassas Campaign of the American Civil War . A Union brigade was ordered to probe the Confederate defenses along Bull Run to locate the Confederate left . At Blackburn ' s Ford , the brigade attempted to cross but Confederate fire broke up the attack and Union commanders decided to cross the creek farther upstream . Background . On July 16 , 1861 , the untried Union army under Brig . Gen . Irvin McDowell , 35 , 000 strong , marched out of the Washington , D . C . , defenses to give battle to the Confederate Army of the Potomac , which was concentrated around the vital railroad junction at Manassas . Moving slowly , the army reached Fairfax Court House on July 17 ; the next day , McDowell ordered division commander Brig . Gen . Daniel Tyler to look for a fording point across Bull Run Creek and to " keep up the impression that we are moving on Manassas " . The Confederates , about 22 , 000 men under the command of Brig . Gen . P . G . T . Beauregard , were concentrated near the Bull Run , with detachments spread north of the creek to observe the Federals . When McDowell started his advance from Washington , the Confederate detachments slowly retreated and rejoined the main body . Beauregard expected to be attacked either on the 18th or the 19th near Mitchell ' s Ford ; meanwhile , he continued to ask for reinforcements , especially from Joseph E . Johnston ' s army in the Shenandoah Valley . Battle . On July 18 , Tyler advanced to Centreville and found that Centreville was unoccupied by Confederate troops . He then marched southeast to Mitchell ' s Ford and Blackburn ' s Ford , arriving at the latter about 11 a . m . Looking south across the stream , Tyler believed that the road to Manassas Junction was clear , but he failed to see the Confederate brigade of Brig . Gen . James Longstreet concealed in the woods behind the ford . He ordered two howitzers under Capt . Romeyn B . Ayres to bombard the Confederates he could see , guns of the Alexandria Artillery and the Washington Artillery , but the fire had no visible effect . He ordered Col . Israel B . Richardson and part of his brigade forward . Richardson ' s advance met initial resistance from the 1st , 11th , and 17th Virginia Infantry regiments of Longstreet ' s brigade . Tyler ordered Ayres to move his guns closer to the action , accompanied by cavalry , and he sent the rest of Richardson ' s brigade toward the ford . Richardson ' s assault fell apart as the 12th New York Infantry began to retreat under heavy fire , causing a wave of panic to spread through the Union line . Col . Jubal A . Early arrived with his Confederate brigade after marching 2 miles north from Beauregard ' s headquarters at Wilmer McLean ' s house . The availability of this additional firepower completed the Confederate victory , and a reinforced Washington Artillery kept the Union troops under fire as they retreated . Colonel Patrick T . Moore of the 1st Virginia Infantry , later a Confederate brigadier general , received a severe head wound in the skirmish and was incapacitated for further field service . Aftermath . The failed reconnaissance - in - force at Blackburn ' s Ford led McDowell to decide against a frontal assault along Bull Run . He decided to attempt to cross the stream beyond the Confederate left flank , the maneuver he employed at the First Battle of Bull Run on July 21 . Both Longstreet and Early claimed later that the battle " went a long way towards winning the victory of the 21st , for it gave our troops confidence in themselves " .