From Frederick to Sharpsburg: People, Places, and Events of the Maryland Campaign Before Antietam: People, Places, and Events of the - Hardcoverby Steven R. Stotelmyer (Author) The Battle of Antietam stands out as the single bloodiest day's combat in American history. More people were killed or injured on September 17, 1862, than any other day in our nation's entire history. With 23,000 casualties it is understandable that this single event tends to take the spotlight in the Maryland Campaign of 1862. However, Robert E. Lee did not begin crossing the Potomac on September 4. 1862, just so he