The Battle and the Campaign

Tactically, Antietam was a draw. Strategically, however, it was a Northern victory because it halted Lee's invasion.

Though McClellan failed to destroy Lee's army, his contribution was in many ways notable. In the 3 weeks after he was chosen for command on September 3, he provided for Washington's defense, created a new field army, fought two major actions, compelled Lee's evacuation of Maryland, and established Federal control of the Potomac River from Washington to Williamsport. That he was not a daring commander of Lee's stripe cannot detract from these solid achievements.

Lee, on the other hand, may have been too daring. Because of this he made two major miscalculations. First, his invasion of Maryland imposed a strain that his poorly equipped and exhausted army could not support; heavy straggling was the surest evidence of this. Second, he misjudged the capacity of the enemy to recuperate from the effects of Second Manassas and quickly put a reliable field army on his trail. He did achieve one of his objectives: The delay of the Federal armies in resuming major offensive operations in Virginia until the next winter. But the price was high and the South could not afford the kind of attrition suffered in the campaign.

Casualties were so heavy in the Battle of Antietam that September 17, 1862, is termed the bloodiest day of the Civil War. Of McClellan's 26,023 killed, wounded, and captured during the Maryland Campaign (including Harpers Ferry), he counted 12,410 at Antietam. Of Lee's 13,385 casualties during the campaign, 10,700 fell at Antietam.