Detachments from two New York regiments were on picket duty on the afternoon of December 2, 1861 at the intersection of the unfinished Manassas Gap railroad roadbed and the Little River Turnpike. Later investigation suggested that some of the soldiers manning the barricade may have been drinking liquor and/or sleeping. At approximately 1 PM, the pickets observed approximately 200 cavalrymen approaching. As the Southerners were wearing blue uniforms, a not uncommon occurrence in the early days of the war, the pickets mistook them for a friendly force. However, the galloping South Carolinians pronounced their unfriendly intentions by unleashing a volley of fire.
A sketch of the December 2, 1861 skirmish between Federal and Confederate forces at Annandale, VA was printed in The Illustrated London News.
However, with reinforcements, the New Yorkers repelled the attack and the Confederates retreated towards Centreville. Union cavalry pursued the southerners for several miles. A New York trooper wrote, "We were stationed in the woods, behind Annandale Church, and hearing the long roll beat, immediately formed in line outside of the woods, and opened a heavy fire on them, and charged. They retreated in all directions, we pursuing them and taking two prisoners and some horses, sabres, and revolvers. The effect of our fire was not ascertained. We had 25 men and the enemy numbered over 150."
In his after-action report, Union Brigadier General Louis Blenker reported that two Confederates were captured and at least two were killed. Only one Union soldier was reported killed in the skirmish. Blenker noted that a local farmer was arrested on suspicion of providing the Confederates with intelligence on the Union position at Annandale and signal had allegedly been seen emanating at night from his farm house. However, Blenker lamented that he did not have enough evidence to hold the secessionist farmer and released him and his sons.