The Trans-Mississippi Department was a militarily administrated subdivision of the Confederate States of America west of the Mississippi, comprising Texas, Arkansas, Missouri, Indian Territory, and parts of Arizona and Louisiana.
The department was formed May 26, 1862, comprising Missouri, Arkansas, Texas, Indian Territory (now Oklahoma), Confederate Arizona (which included parts of New Mexico), and the part of Louisiana west of the Mississippi River. When created, it absorbed the previously established Trans-Mississippi District (Confederate Department Number Two), which had been organized January 10, 1862, to include the Indian Territory, Missouri, Arkansas (except for the country east of St. Francis County, Arkansas to Scott County, Missouri), and that part of Louisiana north of the Red River. The combined department had its headquarters at Shreveport, Louisiana, and Marshall, Texas. It was responsible for the Confederate theater of operations west of the Mississippi. Its forces were sometimes referred to as the "Army of the Southwest."
Because the department was commanded often during its existence by General Edmund Kirby Smith, it became popularly known as "Kirby-Smithdom."
Department Two's commander:
- General Edmund Kirby Smith (January 10, 1862 – May 23, 1862)
The combined department's commanders included:
- Brig. Gen. Paul O. Hébert (May 26, 1862 – June 20, 1862)
- Maj. Gen. John B. Magruder (assigned June 20, 1862, but did not accept)
- Maj. Gen. Thomas C. Hindman (June 20, 1862 – July 16, 1862)
- Maj. Gen. Theophilus H. Holmes (July 30, 1862 – February 9, 1863)
- Lt. Gen. Smith (March 7, 1863 – April 19, 1865)
- Lt. Gen. Simon Bolivar Buckner (April 19, 1865 – April 22, 1865)
- General Smith (April 22, 1865 – May 26, 1865)
- Maj. Gen. Earl Van Dorn (January 10, 1862 – May 23, 1862, when the district was part of Confederate Department Number Two)
- Captain Jarnell "J.T." Hearns (August 27, 1862 – September 1, 1862)
- untitled; Missouri Government online; accessed September 2016