Department of Missouri

The Department of the Missouri was a command echelon of the United States Army in the 19th century and a sub division of the Military Division of the Missouri that functioned through the Indian Wars.

Following the successful conclusion of the Mexican-American War, the administration of the United States Army was theoretically directed, under the President of the United States, by the Secretary of War and the general in chief. In practice the Secretary of War and the heads of the army's staff agencies—who reported directly to him (adjutant general, quartermaster general, commissary general, inspector general, paymaster general, surgeon general, chief engineer, colonel of topographical engineers, and colonel of ordnance)—exercised full authority, leaving the general-in-chief a figurehead. With a lack of central direction, policy and strategy were de facto developed by the commanders of the numbered geographical departments and three division headquarters. After October 31, 1853 the division echelon was eliminated and the six western departments consolidated into four (Departments of Texas, New Mexico, the West, and the Pacific), whose department commanders employed their troops as they saw fit. The system returned to six departments in 1858 when the Department of Utah was created in January, and the Department of the Pacific split into the Departments of California and Oregon in September.

Military activity affecting one department often originated in another department, preventing efficient use of limited manpower and coordination of efforts. Friction between the Secretaries of War and the generals in chief, and particularly between Jefferson Davis and Winfield Scott, obstructed reforms in the staff system that might have brought unity of command and civilian control of the military. The expansion of the army during the Civil War saw a proliferation in the numbers of geographic departments and their subordinate districts, often changing names and areas under their individual control, some departments eliminated or renamed, only to be recreated again in altered form.

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