This is an excerpt from the book Washington Weather

The Thunderstorm and the Battle of Ox Hill

(Chantilly), September 1, 1862


On a high hill just west of Fairfax, Virginia, a fierce Civil War battle was fought in a blinding thunderstorm on September 1, 1862. Two well-known Union generals were killed, and over two thousand casualties occurred in the dramatic fight that was greatly influenced by a line of thunderstorms associated with a strong cold front. The Battle of Ox Hill (or Chantilly) is also known as the only major Civil War battle to have been fought during a storm. To gain a full appreciation of the role that the weather played in the battle – as well as influencing the events that occurred later in the Civil War – the full context of the event needs to be explained:

In the closing days of August 1862, Union General John Pope’s Army of Virginia suffered a defeat at the Battle of Second Manassas. The Union army, beaten but still intact, retreated to Centreville, Virginia and was heading back to the fortifications around Washington. General Lee, commander of the Confederate Army, hoped to stop the Union Army’s retreat by circling around the Union forces and blocking their route. The location that General Lee had chosen to stop the Union Army was the Jermantown crossroad, located just west of Fairfax, Virginia.

Lee’s strategy was to take Stonewall Jackson’s Corps around the north side of the Union Army in a long, flanking move. To divert attention from Jackson’s flanking move, Longstreet’s Confederate Corps stayed visible behind the Union Army. Meanwhile, Jeb Stuart’s cavalry of 5000 rode ahead of Jackson’s Corps to scout Pope’s movements. Lee had planned for his armies to converge at the crossroad and block Pope’s Union Army. As this maneuver began, there were cloudy skies with an increasing southerly wind. Clouds were noted to “race across the sky.” Threatening weather was looming.

As Jackson’s men were circling around the Union Army, Pope began to realize that a flanking move was underway by the Confederates, partly because Jeb Stuart had attacked a wagon train east of Chantilly. This alarmed Pope who sent Union General Issac Stevens and a small force of 4000 soldiers towards the Confederates. Stevens’ forces surprised Jackson’s men at Ox Hill, near the present day West Ox Road. Jackson abandoned his march towards the crossroads and went into a defensive position. At this time, the sky was darkening and the wind was blowing strong from the south, with flashes of lightning on the horizon

General Stevens, knowing he had surprised Jackson, made a courageous decision to immediately attack the Confederate brigades who were just starting to deploy into a defensive line. Stevens’ first advance stalled in the face of a massive volley that caused numerous casualties among the Union ranks, including the general’s son, Captain Hazard Stevens. The fighting began around 4:30 p.m., about the same time the thunderstorms were moving in.  General Stevens, distraught about having seen his son fall in battle, decided to attack again while Jackson was still off balance. He grabbed a regimental flag from a wounded color bearer and personally led the charge. General Stevens was an easy target holding the battle flag and was quickly shot and killed. By now, the rain had started to fall heavily and began causing the soldier’s black powder rifles to become unserviceable. With the rain in their favor, the outnumbered Union soldiers crashed through the center of the Confederate line. The Confederates, disorganized and confused, withdrew in considerable disorder. As the Confederates retreated, General Jubal Early’s Brigade of Virginians arrived, filled the breach, and stopped the Union breakthrough from becoming a rout.

     As the fighting continued, the sky became as dark as night and the thunderstorm lashed the soldiers with extremely heavy rain, strong winds and frequent lightning. The booms of cannons mixed with the loud explosions of thunder. The storm reduced visibility and the soldiers had a difficult time seeing their enemy. Sheets of rain blew horizontally across the battlefield, soaking the soldiers. Private Greely of the 19th Massachusetts recorded:


 The roll of musketry and the roar of cannon left all of us unmoved, but the crash of thunder and the vividness of the lightning, whose blinding flashes seemed to be in our very midst, caused the uneasiness and disturbance among some of the bravest men.


The storm and rain continued as did the battle, and the intensity of the fighting did not diminish. Although the Confederates were caught off-guard by the Union attack, the hardened and tenacious Confederate veterans began to take control of the battle. The Union soldiers were slowly being driven back through the mud and rain. Fortunately, for the retreating Union troops, General Philip Kearney arrived with reinforcements. Hoping to reinvigorate the attack and urge the Union forces forward, Kearney pushed ahead of his men. With terrible visibility from the storm, General Kearny rode right up to the Confederate line. When he realized his mistake, he turned his horse and galloped through the thick mud back towards his division. The Confederates opened fire and Kearny was shot off of his galloping horse and was killed.

 As the drenching rain continued, dry black powder cartridges became scarce and rifles misfired so often that the commanders told their troops to “give them the bayonet.” A series of bayonet charges ensued. Finally, after over two hours of fierce hand-to-hand fighting, the heavy rain and cold temperatures began to dampen the will of the soldiers to fight. The Union army withdrew in the darkness and the Confederates held the field. Technically, it was a Confederate victory, but Lee had failed to accomplish his goal of stopping Pope’s Army. The Union Army retreated to Washington, and the Confederates later turned north, setting the stage for the bloody Battle of Antietam.

The thunderstorms that occurred during the battle were associated with a strong, early-season cold front. The front was also accompanied by strong winds. Before the battle, the wind was strong from the south, recorded by the Naval Observatory in Washington to be at “Force 6.” (The Wind Force Scale ranged from 1 to 10 and was based on estimation.)  The next day, on September 2, the Naval Observatory recorded winds from the northwest at “Force 4,” and military records noted that northwest gales hampered shipping on the Potomac River. The Naval Observatory also recorded that 1.08 inches of rain fell during the storm of September 1, and they included the following remark:  “Commenced an exceedingly heavy rain, with lightning and thunder, at 5:45 p.m.

The loss of Kearny and Stevens was a tremendous blow to the Union. Both men were popular and well-respected generals. In honor of Kearney, the U.S. Army began the tradition of awarding medals called the Kearny Cross for acts of courage. Soon afterwards, Congress authorized what is now known as the Congressional Medal of Honor. Hazard Stevens, General Stevens’ son, recovered from his injuries suffered during the battle.

The Battle of Ox Hill was eventually forgotten, overshadowed by the Battle of Second Manassas and by Lee’s invasion of the North. However, had the fierce thunderstorms not occurred, the Battle of Ox Hill may have turned out quite differently, potentially altering the course of the war. Without the storm, the Confederates had a good chance of stopping General Pope and making a move on Washington.

Currently, there are monuments to the Battle of Ox Hill at Fairfax Towne Center, which is located on the northeast side of the battlefield.