Across the Potomac -- McClellan in command -- Lee divides his forces -- The lost order -- Fighting for time at South Mountain -- Harpers Ferry surrenders -- Lee takes a stand on Sharpsburg Ridge -- McClellan concentrates at the Antietam -- The lines are poised for action -- Hooker strikes at daybreak -- Mansfield renews the attack -- Jackson prepares an ambush -- The fight for the sunken road -- Burnside takes the lower bridge -- A.P. Hill turns the tide -- Retreat from Sharpsburg -- The battle and the campaign -- The war for the Union takes on a new purpose -- Clara Barton at Antietam -- Antietam National Battlefield Site and Cemetery -- Administration -- Suggested readings -- Appendix.