On December 18, 1862, the U.S. War Department issued General Orders No. 210, creating four Army Corps from troops operating in Missouri or near the Mississippi River.
General Orders No. 210.
War Dep’t, Adjutant General’s Office
Washington, December 18, 1862
By direction of the President, the troops in the Department of the Tennessee, and those in the department of the Missouri, operating on the Mississippi river. Will be divided into four Army Corps, to be numbered the Thirteenth, Fifteenth, Sixteenth, and Seventeenth.
Major General J.A. McClernand is assigned to command the Thirteenth Army Corps;
Major General W.T. Sherman to the command of the Fifteenth Army Corps;
Major General S.S. Hurlbut to the command of the Sixteenth Army Corps;
Major General J.B. McPherson to the command the Seventeenth Army Corps.
By Order of the Secretary of War:
E.D. TOWNSEND, Assistant Adjutant General