Jackson, meanwhile, covered by the cavalry, was advancing to Chantilly—­a fine old mansion which the Federals had gutted—­with the intention of seizing a position whence he could command the road.  The day was sombre, and a tempest was gathering in the mountains.  Late in the afternoon, Stuart’s patrols near Ox Hill were driven in by hostile infantry, the thick woods preventing the scouts from ascertaining the strength or dispositions of the Federal force.  Jackson at once ordered two brigades of Hill’s to feel the enemy.  The remainder of the Light Division took ground to the right, followed by Lawton; Starke’s division held the turnpike, and Stuart was sent towards Fairfax Court House to ascertain whether the Federal main body was retreating or advancing.

Reno, who had been ordered to protect Pope’s flank, came briskly forward, and Hill’s advanced guard was soon brought to a standstill.  Three fresh brigades were rapidly deployed; as the enemy pressed the attack a fourth was sent in, and the Northerners fell back with the loss of a general and many men.  Lawton’s first line became engaged at the same time, and Reno, now reinforced by Kearney, made a vigorous effort to hold the Confederates in check.  Hays’ brigade of Lawton’s division, commanded by an inexperienced officer, was caught while “clubbed” during a change of formation, and driven back in disorder; and Trimble’s brigade, now reduced to a handful, became involved in the confusion.  But a vigorous charge of the second line restored the battle.  The Federals were beginning to give way.  General Kearney, riding through the murky twilight into the Confederate lines, was shot by a skirmisher.  The hostile lines were within short range, and the advent of a reserve on either side would have probably ended the engagement.  But the rain was now falling in torrents; heavy peals of thunder, crashing through the forest, drowned the discharges of the two guns which Jackson had brought up through the woods, and the red flash of musketry paled before the vivid lightning.  Much of the ammunition was rendered useless, the men were unable to discharge their pieces, and the fierce wind lashed the rain in the faces of the Confederates.  The night grew darker and the tempest fiercer; and as if by mutual consent the opposing lines drew gradually apart.* (* It was at this time, probably, that Jackson received a message from a brigade commander, reporting that his cartridges were so wet that he feared he could not maintain his position.  “Tell him,” was the quick reply, “to hold his ground; if his guns will not go off, neither will the enemy’s.”)

On the side of the Confederates only half the force had been engaged.  Starke’s division never came into action, and of Hill’s and Lawton’s there were still brigades in reserve. 500 men were killed or wounded; but although the three Federal divisions are reported to have lost 1000, they had held their ground, and Jackson was thwarted in his design.  Pope’s trains and his whole army reached Fairfax Court House without further disaster.  But the persistent attacks of his indefatigable foe had broken down his resolution.  He had intended, he told Halleck, when Jackson’s march down the Little River turnpike was first announced, to attack the Confederates the next day, or “certainly the day after.”