Wikipedia
The Battle of Fairfax Court House (June 1863) was fought during the Gettysburg Campaign of the American Civil War between two cavalry detachments from the Union Army of the Potomac, commanded by General Joseph Hooker, and the Confederate Army of Northern Virginia, commanded by General Robert E. Lee.
The Confederate cavalry leader General J.E.B. Stuart was keen to restore his prestige after two humiliating encounters with Union cavalry, and as the main body crossed the Potomac into Maryland, he received permission to detach three brigades and ride around the entire Union army to gather supplies and intelligence, and damage lines of communication.
At Fairfax Court House, Virginia, on 27 June, one of Stuart’s brigades, led by Brigadier General Wade Hampton, was surprised by a small detachment of the 11th New York Cavalry under Major Remington, which initially drove them into the woods, but were so heavily outnumbered that they had to retreat. Although technically a Confederate win, this small engagement had a major impact on the outcome of Gettysburg, since it delayed Stuart’s arrival, depriving Lee of essential knowledge of the enemy’s whereabouts.