Completed in the early 1900s, The Maryland Campaign of September 1862 is still the essential source for anyone seeking understanding of the bloodiest day in all of American history. As the U.S. War Department's official expert on the Battle of Antietam, Ezra Carman corresponded with and interviewed hundreds of other veterans from both sides of the conflict to produce a comprehensive history of the campaign that dashed the Confederacy's best hope for independence and ushered in the Emancipation Proclamation. Nearly a century after its completion, Carman's manuscript has finally made its way into print, in an attractively packaged one-volume edition painstakingly edited, annotated, and indexed by Joseph Pierro. This edition, the first to publish the entire Carman manuscript, including the fifteen appendices, is designed for ease of use, with standardized punctuation and spelling, and conveniently footnoted explanations wherever necessary. The Maryland Campaign of September 1862 is a crucial document for anyone interested in delving below the surface of the military campaign that forever altered the course of American history, and is still the only complete edition of Carman's work on the market. **Due to an unfortunate case of mistaken identity, the man currently appearing in the frontispiece of The Maryland Campaign of September, 1862 is not the actual Ezra Carman, but someone who looks remarkably similar to him. The real Mr. Carman can be found at: http://www.loc.gov/pictures/item/cwp2003001783/PP/. We apologize for the mistake, and will correct this error in further printings.