The farm of Joseph and Mary Ann Poffenberger is on the far north end of the Antietam battlefield, north of Mansfield Road. (Mansfield Avenue tour map) As troops began moving into the Sharpsburg area the Poffenbergers locked up their buildings and moved themselves and their livestock to safety.

When troops of the Union 1st Corps moved across Antietam Creek the evening before the battle they clashed with Confederate skirmishers on part of the Poffenberger farm fields. The Union 1st Corps then used the farm as a staging area for its attack the next morning.