On September 1, 1862 the Batlle of Ox Hill at Chantilly was fought during severe thunderstorms. It was one of the only battles of the Civil War known to be fought under stormy weather conditions. While our military troops currently view adverse weather and low visiblity environments to be advantageous, this was not the case for troops in the Civil War era. Military tactics at this time favored engagements between large numbers of troops, and so stealth was not usually a primary concern. Combat during the Civil War was always brutal beyond belief, but the weather conditions at this engagement led to even more confusion and difficult fighting conditions than usual.
Prior to the Battle of Chantilly, Union troops had been defeated at the second Battle of Manassas. Exhausted and battle weary, they were retreating toward Washington to regroup. The Confederate troops attempted to flank their movement and cut off their retreat. A small skirmish alerted the Union commanders to the Confederate movements and they responded by attacking the Confederate troops. This caught the Southern troops by surprise at Ox Hill. The Union army attempted to exploit the advantage of surprise by pressing the attack as the Confederate troops dug in at Ox Hill. Meanwhile, a very strong cold front was passing through the area, which led to the severe storms which were a decisive factor in the outcome of this battle. While technically a Confederate victory, the Southern troops did not accomplish their goals in this battle or its aftermath.
The weather on this day was notable due to an extremely strong early season cold front – the exact kind of cold front many are wishful for this year but we currently can find no sign of on the horizon. It was clearly strong and Canadian in origin, and being only September 1, was pushing into hot and humid summer conditions. This is a recipe for severe thunderstorms, and that matches perfectly with the accounts from the Battle of Ox Hill. Prior to the passage of the cold front, winds were observed out of the south. After the passage of the front, the winds had shifted to the northwest and became quite gusty. The storms produced very heavy rain, strong winds from the downbursts, and frequent cloud to ground lightning. Some of these storms passed directly over the battlefield.
These Civil War troops were battle hardened veterans. They were accustomed to the intense fighting conditions of Civil War battlefields, including close proximity to rifle and cannon fire as well as hand to hand combat. Dealing with those conditions while also enduring severe thunderstorms was a challenge to even the most experienced of these men. A firsthand account from one Private Greely in the Union army is indicative of this: ”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.”
Early on in the battle, General Isaac Stevens of the Union army was killed as the storms were just getting underway. Having seen his son felled by enemy fire, he led the Union charge while holding the battle flag. This made him an obvious target for the enemy and he was subsequently shot and killed. He was not the only Union general to die by enemy fire on this day. Union General Philip Kearny led the Northern reinforcements that arrived on the battlefield later that afternoon. Arriving during the height of a thunderstorm, he became disoriented by the limited visibility and rode directly into the Confederate lines. Once he realized his error, he turned and tried to ride away but was shot down before he could retreat to his own lines.
The torrential rainfall caused issues with the rifle ammunition. Unable to keep their powder dry, both sides affixed bayonets and resorted to hand to hand combat. This 19th century battlefield had turned medieval, with a huge group of soldiers fighting with blades and clubs in a brutal fight for survival. Estimated casualty figures from this battle are over 2000. While the Battle of Ox Hill is not one of the more famous Civil War engagements, there was a lot at stake here; the outcome was dictated in large part by the weather conditions. After hours of fighting in terrible conditions, the battle slowly came to an end as the sun went down. The men on both sides were very tired and very cold. They had been fighting tooth and nail for hours in the lightning, thunder, and windblown rain. The cold front had now passed and temperatures dropped to fall like conditions.
The results of this battle appeared to favor the South at first glance. The Union had lost two of its most respected and popular generals. The Union troops were the ones who retreated from the battlefield with the setting of the sun on this day, leaving the Confederates in possession of Ox Hill. Upon closer examination, the outcome was not what General Lee had in mind. The Union troops were not stopped from retreating and the defeat was not as crushing as what was originally envisioned. General Lee’s orignal plan was to incapacitate this group, and then turn his attention toward an attack towards Washington. Going in to the battle, the Confederates had superior numbers and a tactical advantage. But when the North was able to begin the battle preemptively, they were able to gain an advantage due to the element of surprise. Added to this, the confusion and chaos caused by the thunderstorms prevented the Confederate army from carrying out its battle plan effectively. In the end, the Northern troops were able to escape and the Southern troops were unable to launch an attack on Washington. The thunderstorms on September 1, 1862 played a huge role in the war, even though this particular battle is not usually listed among the more significant battles of the Civil War.