Darkness set in during a blinding rainstorm. The Confederate artillerists, wearing gum blankets to protect them from the elements of the weather, opened fire on the head of Kilpatrick's advance. As the confusion subsided, the Confederate cavalrymen charged, pushing the Kilpatrick back until they reached the Federal artillery that was positioned near Fountain Dale. 

For several hours, during the blinding thunderstorm in the middle of the night, the battle was carried out in between lightning strikes and muzzle flashes. Six hours of heavy fighting had spilled over to Fairfield Gap as well as Leitersburg while General Kilpatrick gained the South Mountain summit of Monterey Pass. At Fairfield Gap, a portion of the 1st Michigan Cavalry was beaten back by Confederate cavalry while at the Monterey House, two guns of Pennington's battery began shelling the Confederate wagons.

By 3:30 a.m. on July 5th, Kilpatrick successfully reached the turnpike where Ewell’s wagon train was located, capturing and destroying 9 miles worth of wagons, taking 1,360 prisoners and a large number of horses and mules as they moved on toward Ringgold, Maryland.

Monterey Pass is the second largest battle that occurred in Pennsylvania and was the only battle ever fought on both sides of the Mason and Dixon Line, taking place in four counties, Frederick and Washington Counties, Maryland and Adams and Franklin Counties, Pennsylvania. Monterey Pass is situated on the South Mountain range and being a direct route to the Potomac River, it was used by the bulk of the Confederate Army during it’s withdraw from Gettysburg.