The Battle of Antietam

McClellan's Missed Opportunity

In the fall of 1862, the Army of the Potomac under Major General George B. McClellan had a chance to inflict a crushing blow on Robert E. Lee’s Army of Northern Virginia. Following his victory at the Second Battle of Bull Run, Lee moved his army into Maryland, hoping to gain recruits in this crucial border state. He then planned to invade Pennsylvania, possibly reaching Harrisburg, or turn to face the Union army on ground of his choosing. However, on September 13, when Federal forces moved into Frederick, Maryland, following the departure of Lee’s soldiers to Harpers Ferry, Boonsboro, and Hagerstown, Corporal Barton Mitchell of the 27th Indiana discovered a lost copy of Lee’s Order 191, which outlined the movements of Lee’s divided forces. Four days later, Union and Confederate forces clashed outside of Sharpsburg, Maryland resulting in a combined 22,719 dead, wounded, or missing. How did McClellan perform in the Antietam campaign? What were his strategic and tactical strengths and weaknesses?