Confederate Major General JEB Stuart’s cavalry was screening the march being made north by General Robert E Lee’s troops advancing into Pennsylvania. On June 17th 1863 the Union cavalry commander Brigadier General Alfred Pleasonton decided to cut through this screen, by sending Brigadier General David Gregg’s division west out of Manassas Junction on the Little River Turnpike toward the town of Aldie, Virginia.
In the early morning, Confederate Colonel Thomas Munford led the 2nd and 3rd Virginia Cavalry from Upperville on towards the Bull Run Mountains looking for forage and doing some reconnaissance. When he reached Aldie he put out a line of pickets and then moved the rest of his men northwest on the Snicker’s Gap Turnpike. Around 4 pm the Union’s 1st Massachusetts Cavalry ran into Munford’s pickets and pushed them in. The 1st Massachusetts was then confronted by the 5th Virginia Cavalry who pushed the Union back to their main line. Then the 1st joined by the 4th New York Cavalry charged, but the Confederates with some help from some sharpshooters drove the Union Cavalry back and secured their lines and hold of Ashby’s Gap Turnpike. The 1st Massachusetts was trapped in a curve on the Snicker’s Gap Turnpike and lost 198 of their 294 men, one detachment almost eliminated in hand to hand fighting.
Somewhere around 8 pm the fighting died off. Munford took his men and moved west towards Middleburg. The Union lost about 305 men, dead and wounded, the Confederate side had losses of about 110.