This primary source comes from the Records of the Office of the Chief of Engineers.
National Archives Identifier:
305669Full Citation: Croquis of the Battlefield of Prairie Grove, Arkansas. December 7th, 1862. Drawn by T. W. Williams, 15 Ills. Infy; 12/7/1862; Records of the Office of the Chief of Engineers, Record Group 77. [Online Version, https://docsteach.org/documents/document/croquis-of-the-battlefield-of-prairie-grove-arkansas-december-7th-1862-drawn-by-t-w-williams-15-ills-infy, May 2, 2024]