Army of the Frontier The Army of the Frontier was a Union army that served in the Trans - Mississippi Theater during the Civil War . It fought in several minor engagements in Arkansas , Indian Territory , and Kansas . In June 1863 the Army was discontinued but many of its regiments were formed into the District of the Frontier . The army was created on October 12 , 1862 , composed of forces from the Dist . of Southwest Missouri . General John M . Schofield was the army ' s first commander . Prior to this ( from October 1 – 12 , 1862 ) Schofield ' s field army was known as the " Army of Southwestern Missouri " . The Army of the Frontier consisted of three divisions at its largest . They were commanded respectively by James G . Blunt , James Totten , and Francis J . Herron . Units of the army ( mostly Blunt ' s 1st Division ) engaged in several small battles early in the war . The Battle of Prairie Grove in 1862 was the army ' s finest moment of the war . During the campaign General Schofield was absent in St . Louis , therefore General Blunt assumed temporary command of the army while still personally leading the 1st Division . Colonel Daniel Huston , Jr . temporarily replaced Totten in command of the 2nd Division . Both the 2nd and 3rd Divisions were then placed under the overall command of General Herron . Herron replaced Schofield as commander in March 1863 . In May of that year the army ' s 2nd Division under William Vandever fought the battle of Chalk Bluff against a Confederate raid under John S . Marmaduke . The army as a whole was dissolved on June 5 , 1863 , yet remnants were formed into " Herron ' s Division " and sent as reinforcements to the siege of Vicksburg . District of the Frontier . On June 6 the remaining units in Arkansas and the Indian Territory , formerly belonging to the Army of the Frontier , were organized into the District of the Frontier with General Blunt in command . The district was part of the Department of the Missouri and was composed of the Indian Territory , western Arkansas , southwestern Missouri and southern Kansas . With troops from this district Blunt fought and won the Battle of Honey Springs in 1863 , but suffered a defeat at Baxter Springs later that year . Blunt was relieved of command in January 1864 . At the same time the District of the Frontier divided up . The Indian Territory and Fort Smith , Arkansas were designated the District of the Frontier in the Department of Kansas and placed under the command of Colonel William R . Judson . The areas in Arkansas were designated the District of the Frontier in the Department of Arkansas and placed under the command of General John Milton Thayer . Thayer ' s troops were attached to the VII Corps during the Camden Expedition as the " Frontier Division " . On February 23 , 1864 Blunt replaced Judson in command of the District of the Frontier , Department of Kansas . Blunt commanded until April 17 when his district was discontinued . Fort Smith was transferred to Thayer ' s district and the rest of the Indian Territory was divided among other districts . Thayer ' s District of the Frontier continued until February 1 , 1865 when it too was discontinued . Sources . http : / / www . civilwarhome . com / armyoffrontier . htm < br > http : / / www . civilwarchronicles . com / commanders . htm