In the public domain as original works of the United States federal government and/or military
This battle map image could be re-created using vector graphics as an SVG file. This has several advantages; see Commons:Media for cleanup for more information. If an SVG form of this image is available, please upload it and afterwards replace this template with {{vector version available|new image name}}.
It is recommended to name the SVG file “Battle of Marathon Greek Double Envelopment.svg”—then the template Vector version available (or Vva) does not need the new image name parameter.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue
Quoted directly from an email querying copyright status of the map: "You are welcome to use the maps stated below for the purposes outlined in your document license. We do request the following credit line, “Maps Courtesy of the Department of History, United States Military Academy.”"
Their cartographer did not actually specify the exact license of the images they have produced, so I am assuming the strictest tag.
Map of the Battle of Marathon, 490 BC. Taken from http://www.dean.usma.edu/history/atlases/ancient_warfare/battle_martahon_greek_envel.gif, in context http://www.dean.usma.edu/history/atlases/ancient_warfare/battle_marathon_envelopment.html. {{Copyrighte