Bryce, does this site give you any more information?http://en.wikipedia.org/wiki/Army_of_Missouri
[edit] References
Eicher, John H., & Eicher, David J., Civil War High Commands, Stanford University Press, 2001, ISBN 0-8047-3641-3.

The Army of Missouri was an independent military command during the American Civil War within the Confederate States Army, created in late 1864 under the command of Maj. Gen. Sterling Price to invade Missouri. Price's Raid was unsuccessful, and his army retreated to Arkansas.

The Army traces its roots to the Missouri State Guard which was created in 1861 under Sterling Price to enforce Missouri's official stance at the beginning of the war of being an "armed neutral" not supporting either side in the conflict while staying in the Union. The Guard eventually became part of the Confederacy after engaging in skirmishes with the Union troops under Nathaniel Lyon who successfully removed elected Governor Claiborne Jackson and replaced him with a pro-Union government.

By the late summer of 1864, a good portion of the Union Army forces from Missouri had been reassigned eastward to aid in efforts to capture Atlanta and to help in other campaigns. The President of the Confederate States of America, Jefferson Davis had the War Department order E. Kirby Smith, commander of the Trans-Mississippi Department, to send his infantry across the Mississippi River to reinforce beleaguered Confederate troops in the east. However, Smith had alternative plans, desiring to "liberate" Missouri from Federal control, seizing the key cities of St. Louis and the state capital, Jefferson City and reinstating the Confederate governor and his supporters to power. Smith decided to send a large force of mounted infantry and cavalry under former Missouri governor Sterling Price to carry out his plan.

Price's "Army of Missouri" had three divisions, led by Maj. Gen. James F. Fagan, Maj. Gen. John S. Marmaduke and Brig. Gen. Joseph O. Shelby, all veterans of considerable previous combat. The column was accompanied by fourteen artillery pieces. Price was unable to procure enough small arms for his men, and nearly half left northeastern Arkansas on Friday, September 16, 1864, without weapons. After some initial success, Price's force was soundly defeated at the Battle of Westport by the pursuing Federal Army of the Border and forced to retreat. The Union troops won another victory at Newtonia, but failed to crush Price's army, which retired through Kansas and Indian Territory before heading on to eastern Texas to avoid additional Federal troops at Fort Smith, Arkansas. The remnants of Price's weary army finally returned to Arkansas on December 2, having lost about 6,000 men. The remains of the Army of the Missouri were absorbed into the Trans-Mississippi Army and Price commanded its Cavalry Corps from December 3, 1864, to March 12, 1865.

Instead of officially surrendering at the end of the Civil War in 1865, Price led many of his remaining men to Mexico in exile.
Sincerely,
Fran Bolton