2The Battle of Antietam, widely known as the bloodiest day in American history, was also a pivotal point in the Civil War. The battle itself was a draw, but it ended Robert E. Lee's first attempt at invading the North when his troops withdrew back across the Potomac in the aftermath of the engagement. The outcome of the battle caused President Lincoln to reevaluate the performance of his general George B. McClellan, a decision that altered the outcome of the war. Author David Keller provides a fresh look at the command decisions of Robert E. Lee and George B. McClellan before, during and after the Battle of Antietam, with insight into President Lincoln's evaluation of McClellan and his use of the Battle of Antietam for political purposes.