It sounds like there are at least two different "Camp Hardeman" but I believe the one below was named for Lt. Col. Peter C. Hardeman and was located near the Choctaw-Arkansas line near Sugar Loaf Creek south of Ft Smith.
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HDQRS. DEPARTMENT OF THE INDIAN TERRITORY,
Camp Hardeman, November 1, 1863.
Brigadier General D. H. COOPER,
Commanding Second Brigade:
GENERAL: I shall to-morrow withdraw the Texas brigade to the rear for clothing and other supplies. You will dispose of your brigade in such a manner as to enable you to continue the system of annoyance now carried on by the Choctaws, harassing the enemy without risking an engagement of your whole force. You will keep me advised of any movements the enemy may make, in time, if possible (should he move south), to place Gano's brigade in his front. My opinion is that if any movement is made in the direction of Red River this winter, it will be by the Line road; it will be necessary to watch from a movement on that road. It is hoped that, by withdrawing a portion of the troops, a supply may be accumulated at different points for your future operations.
Respectfully, your obedient servant,
WM. STEELE,
Brigadier-General, Commanding.
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As I recall... Cooper was on either the Butterfield Route or the California Road (aka Beale's Wagon Road) between Ft Smith and Perryville watching for southern movements from either Ft Gibson or Ft Smith into the Choctaw Nation -- which Steele is telling him to go back to doing in the above correspondence.
Gano on the Line Road (Ft Smith-Jenny Lind-Waldron-Dallas Ark-Laynesport) from Ft Smith to the Red River. Cooper south of Ft Smith to Sugar Loaf with the idea of attacking that place. Gano joined him there.
Steele was concerned about why Cooper moved and thought he was going to attach Ft Smith without consulting him so he went in person to Gano's camp (Camp Hardeman) near Cooper's camp.
Steele writes to Cooper from Camp Hardeman telling him Gano will move south for the winter. Gano is ordered to Doaksville and expected to guard the Line Road (Choctaw-Arkansas Line Road) to prevent an advance into North Texas via Laynesport AR.
As I remember, it is rather difficult to follow Steele's movements during this time. I beleive he was with Cooper, then went to Shreveport to see Kirby Smith in person, then maybe to Sugar Loaf, and then to Boggy Depot. This is from memory, it would take piecing together the reports of Steele, Cooper, etc. during October and November 1863 to track his movements.
Kirby Smith and Steele expected a winter advance, if there was one, to come from Ft Smith either down the Line Road to Laynesport or down the Ft Towson Road (which they apparently didn't know was practically impassible by artillery and trains).
When Maxey replaced Steele in Dec 1863, Gano was near Laynesport in the Choctaw Nation and Tandy Walker was at Doaksville/Ft Townson with a battalion at Lennox Mission (on the south side of "the divide" -- Winding Stair Mountain). The Confederates believed any advance would come from Ft Smith, not Ft Gibson. Cooper believed there was no chance of an advance down the Ft Towson Road and the advance would come down the Butterfield Road (Ft Smith-Boggy Depot Road) and then into North Texas via Colbert's or Rock Ferry. I believe this is why Phillips' Expedition into the Seminole and Chickasaw Nations was such a surprise and there were virtually no opposing forces.