After the Battle of Antietam in September 1862, Gen. Robert E. Lee's Army of Northern Virginia escaped to Virginia while President Abraham Lincoln pressed Union Gen. George B. McClellan to pursue it under a plan to trap Lee in the Shenandoah Valley. On November 1, Union cavalry Gen. Alfred Pleasonton began the advance from Philomont toward Upperville, but Gen. J.E.B. Stuart's cavalry delayed him for three days. On November 3, Stuart's 900 troopers and 12 guns were stretched thinly across a two-mile line near Unison as Pleasonton approached from the north with 4,000 men and 18 guns, advancing with cavalry, infantry, and artillery by roads and fords. Stuart's line held for almost the entire day before a Union infantry attack broke his right flank, forcing a retreat across the fields and along Ashby's Gap Turnpike through Upperville until Confederate cannon fire from Ashby's Gap stopped the Federal pursuit. Though the three days of fighting ended in Stuart's retreat, he accomplished his mission, because Lee's army reached Culpeper County that same day and blocked any Union march on Richmond, foiling Lincoln's plan. On November 5, after learning that Lee had escaped the trap, Lincoln ordered McClellan relieved and replaced two days later by Gen. Ambrose E. Burnside. The following year, during Lee's march through the Shenandoah Valley to invade Pennsylvania, Stuart and Pleasonton fought here again, and Stuart once more screened Lee's army from Pleasonton's cavalry. Ida Dulany watched the action from Oakley Plantation and recorded artillery fire and exploding shells as Union troops surrounded the house.