After the Battle of Antietam on September 17, 1862, Confederate Gen. Robert E. Lee moved his army back across the Potomac River into Virginia (now West Virginia) near Shepherdstown. Union troops followed and attacked on September 19, starting the two-day Battle of Shepherdstown.

Union forces crossed the river and fought Confederate troops guarding the crossing. A mistake by a Confederate general led Lee to send more soldiers back to defend the area. On September 20, heavy fighting broke out as Union troops tried to retreat across the river under fire. Around 700 soldiers were killed, wounded, or captured, making it the bloodiest battle in West Virginia during the war.

This battle ended the Confederate invasion of the North and convinced both sides to stop fighting in the area. A few days later, President Lincoln issued the Preliminary Emancipation Proclamation, which announced plans to free enslaved people in the Confederate states.