Union casualties were reported to be 250 on the first day of the battle

One of the facts about the Battle of Middleburg is that Union casualties were reported to be 250 on the first day of the battle. Stuart formed his headquarters in Middleburg and dispersed his brigades over the Loudoun Valley to keep an eye out for enemy movement. Col. Alfred N. Duffié, a French-born general, led the 280 soldiers of the 1st Rhode Island Cavalry west from the Army of the Potomac's camp in Centreville early in the morning. Confederate commanders couldn't believe that a small Union regiment would dare to venture thus deep into the enemy country without an escort, therefore Chambliss refrained from attacking aggressively, fearing that the column was the advanced part of a much bigger enemy force. Duffié continued his solitary march, turning north at about 11:00 a.m. and following orders to Middleburg.

Duffié arrived and promptly ordered Beverly Robertson to advance to Middleburg to defeat the Union cavalry. Duffié barricaded Middleburg's streets, dismounted half of his regiment behind stonewalls, and requested assistance from Judson Kilpatrick's brigade in Aldie. Stuart's attack routed the heavily outnumbered Rhode Islanders around 7:00 p.m. Many of Duffié's men were apprehended the following morning as Chambliss shut off their escape path. Finally, the Parisian colonel returned to Centreville with only four officers and 27 soldiers. A few stragglers eventually rejoined the regiment's broken remnants. Duffié never served with the Army of the Potomac again, though he did command cavalry in other Union armies. On July 17, 250 Union casualties were reported.