This primary source comes from the Records of the Office of the Chief of Engineers.
National Archives Identifier:
305578Full Citation: Map of the Battle of the Antietam fought on the 16th and 17th September 1862 between the United States Forces under the Command of Maj. Genl. Geo. B. McClellan and the Confederates under Genl. Robt. E; 10/1862; Records of the Office of the Chief of Engineers, Record Group 77. [Online Version, https://www.docsteach.org/documents/document/map-of-the-battle-of-the-antietam-fought-on-the-16th-and-17th-september-1862-between-the-united-states-forces-under-the-command-of-maj-genl-geo-b-mcclellan-and-the-confederates-under-genl-robt-e-lee, April 27, 2025]