SHEPHERDSTOWN, W.Va. -- After surviving the bloodiest single-day battle fought on American soil on Sept. 17, 1862, on farmland surrounding Antietam Creek on the outskirts of Sharpsburg, Md., Confederate troops in Robert E. Lee's Army of Northern Virginia began retreating across the Potomac River near Shepherdstown late the following day.
As the battle-worn Southern troops splashed their way across the river at Boteler's Ford into what is now Jefferson County, W.Va., their crossing was observed and protected by Confederate artillerymen manning 35 cannons stationed in the bluffs behind the Potomac's south shore. The day before the Battle of Antietam began, Lee had ordered Maj. Gen. William N. Pendleton to secure the crossing with the cannons and a contingent of infantry troops, to ensure a safe route of retreat in the event it was needed.
By early afternoon on Sept. 19, the last of Lee's surviving infantry troops had made it back to what was then the Virginia shore, and the Confederate commander ordered Gen. J.E.B. Stuart to lead cavalry troops to a second Potomac River crossing near Williamsport, Md.
As the last of Lee's infantrymen waded up the south bank of the Potomac at Boteler's Ford, a scouting force of Union cavalrymen led by Brig. Gen. Alfred Pleasonton arrived at the Maryland side of the ford and spotted Pendleton's artillery batteries and troops occupying the high ground on the opposite shore.
Gen. George B. McClellan, the Union Army commander, had ordered Pleasonton not to cross the Potomac and pursue the retreating Confederates "unless you see a splendid opportunity to inflict great damage upon the enemy without loss to yourself." Seeing that the south side of the ford was well defended, Pleasonton ordered 70 cannons to be placed on the north side of the Potomac. While he did not directly engage the enemy with his troops, Pleasonton did not hesitate to order his batteries to open fire on the Confederate positions across the river.
The Confederate cannons returned fire, but as night approached nearly 500 Union troops crossed the river after Pleasonton received orders from McClellan to attack Lee's rear guard. Outgunned and unnerved by the attacking federal troops, who had begun to engage his infantry and seize several of his cannons, Pendleton left his position on the West Virginia shore in a bid to round up reinforcements.
Pendleton, a West Point graduate who left the Army prior to the war to become an Episcopal clergyman, came across Lee shortly after midnight, and told him that Union troops had seized all his artillery and taken control of the Potomac's south shore at Boteler's Ford. In fact, the federal force had captured only five cannons, and in his absence, Pendleton's men managed to safely withdraw the remaining artillery and troops to new positions a short distance inland.
Early Sept. 20, hundreds of Union troops began streaming across the Potomac to join the 500 already in Jefferson County. But as they headed inland, they soon began meeting stiff resistance from reinforcements that had arrived from Gen. Thomas J. "Stonewall" Jackson's command. After Union commanders determined they were outnumbered nearly two to one by the Confederates, the northern troops were ordered back to the Maryland shore. Many of them did not manage to re-cross the Potomac before coming under fire from Confederate troops.
Among the federal soldiers pinned down along the Potomac's bluffs were members of the 118th Pennsylvania Volunteers, a unit only 20 days in the field and never before tested in combat. The Pennsylvania regiment, funded by the Philadelphia Corn Exchange and nicknamed the Corn Exchange Regiment, was one of the last federal units to withdraw from the West Virginia shore. While other Union soldiers splashed back to safety in Maryland, the 118th's commander held his position because he mistakenly believed had not received a valid order to retreat.