In an increasingly apprehensive search for Gen. Robert E. Lee’s army, Union Maj. Gen. Joseph Hooker, from his headquarters in Fairfax, Va., sent his cavalry to the west and an intelligence agent to the north, to pinpoint the Army of Northern Virginia’s location.
Lee was marching northward down the Shenandoah Valley, behind the cover of the Blue Ridge Mountains and Maj. Gen. J.E.B. Stuart’s cavalry screen, as his invasion of the North continued. (See Coastal Point, June 13 and June 20, 2014).
Beginning June 17, Union cavalry commander Brig. Gen. Alfred Pleasonton had driven Stuart’s forces slowly but relentlessly toward the mountains. Once the Yankees pushed Stuart back to the Blue Ridge on June 21, however, they were greeted by one of Lee’s infantry divisions, which blocked Ashby’s Gap, leading to the Shenandoah Valley.
Pleasonton, unabashed by his failure to locate the rebel army, declared victory in a message to headquarters (from the War of the Rebellion Official Records): “Being satisfied I had accomplished all that the expedition designed, I returned to [Aldie].” In other words, he withdrew from contact with the enemy, while leaving his commander still in the dark concerning Lee’s whereabouts.
Once Lee learned that the Union cavalry threat against Stuart had dissipated, he ordered Lt. Gens. A.P. Hill and James Longstreet to lead their infantry corps toward the Potomac. On June 22, he directed Lt. Gen. Richard S. Ewell, already in Maryland, to move into Pennsylvania: “I think your best course will be toward the Susquehanna [River].”
Realizing that Ewell would not have a sizable enough cavalry force with his corps in Pennsylvania, Lee advised Stuart on June 23 to leave two brigades behind to guard the army’s rear and cross into Maryland with his other three brigades — then on to Pennsylvania.
Given information that ranger battalion commander Maj. John Mosby had gathered regarding the Army of the Potomac’s scattered positions in front of Washington, Lee gave Stuart permission to take a shortcut through the Union army, into Maryland.
Meanwhile, Hooker sent John Babcock, a civilian intelligence agent, into Maryland. He arrived in Frederick on June 19 and established a base of operations with Hiram Winchester, the pro-Union principal of the Frederick Female Seminary.
Hooker’s orders were: “Employ and send persons on to the heights of South Mountain, to overlook the valley beyond and see ... if the enemy has any considerable number of his forces on the north side of the Potomac.”
This precarious assignment nearly ended badly for Babcock on June 20, when Confederate cavalry suddenly dashed into town. Although he managed to avoid them, Babcock was aware that, if captured, he soon would be hanging from the nearest tree, as a spy.
Before attempting a hazardous expedition through the Union army, Stuart sent Mosby back across the Bull Run Mountains to reconnoiter. On June 23, Mosby rode behind enemy lines and learned that Hooker’s army remained stationary.
Armed with this latest intelligence, in the early morning hours of June 25, Stuart led his cavalry east toward the Union position. As he later reported, his plan was to “attain the enemy’s rear, passing between his main body and Washington, and cross into Maryland.”
As daring as this maneuver was, it appeared to be achievable. That is, until Hooker received a message on June 24 from Babcock — his eyes and ears in Maryland — saying he had learned that the corps of “Longstreet and A.P. Hill are crossing [the Potomac] rapidly.” As a result, on June 25, Hooker directed his army to move across the river into Maryland in pursuit of Lee’s forces.
When Stuart’s brigades arrived east of the mountains that day, they unexpectedly encountered a Union corps marching northward and blocking their path. In a quandary on how to react, Stuart chose to make a wide loop to the south and east, around the marching Yankee army. The option would have been to retreat to the Blue Ridge and head to Pennsylvania over a much longer route.
This maneuver would cause the cavalry commander to be separated from Lee and the main army for the next seven days — an eternity during a military campaign. Without Stuart to guide his army, Lee would be virtually blind.
Although unknown at the time, Stuart’s separation from Lee was a direct result of Babcock’s intelligence reporting from Maryland. That separation would weigh heavily as the armies moved closer to an historic engagement.
Bethany Beach resident Thomas J. Ryan is the author of “Essays on Delaware during the Civil War: A Political, Military and Social Perspective” (available at Bethany Beach Books or from his website at www.tomryan-civilwar.com). Contact him at firstname.lastname@example.org.