From Warde's When the Wolf Came: The Civil War and the Indian Territory, page 200.

"Some in the Indian nations were questioning the wisdom of their Confederate alliances, when in February 1864 Col. William A. Phillips launched another invasion from Fort Gibson aimed at reclaiming them for the Union. Going almost as far south as Fort Washita, his troops burned whatever might be of use to the Confederate allies. At Middle Boggy on February 9, 350 Union cavalrymen commanded by Maj. Charles Willets, along with a section of artillery, found about 90 men of the 1st Choctaw and Chickasaw Mounted Rifles and a detachment of the 20th Texas Cavalry. Captain Adam Nail, a Choctaw officer, quickly went for help from Col. John Jumper's Seminoles, camped nearby."

The Battle of Middle Boggy was on February 13, 1864. On the 9th, Phillips hadn't crossed the Canadian yet.

In January 1864, Gen. S.B. Maxey assigned Col. Tandy Walker to command of the 2nd Indian Brigade with headquarters at Doaksville, just north of the present town of Fort Towson OK, and charged with guarding the old Fort Smith - Fort Towson Military Road. Command of the 1st Choctaw & Chickasaw passed to Lt. Col. James Riley, who was posted at Lennox Mission, just northeast of present Talihina OK. There is no record of any portion of the regiment being in the western Choctaw Nation, far removed from the rest of the regiment and their brigade.

Capt. Adam Nail was the original commander of Co. A, 1st Choctaw & Chickasaw. He died in late 1861. He was succeeded by Capt. William B. Pitchlynn who was in command of the company in the Nov-Dec 1861 in the battles with Opothleyahola.

Bass' 20th Texas Cavalry (dismounted) was precisely that, "dismounted". From casualties but mostly from desertions, the 'regiment' only numbered about 200 men and was used for garrison duty. It had been ordered to Boggy Depot by Maxey. There is no evidence that any of them were present at the Battle of Middle Boggy.

Cooper reported the troops in the battle were the "Seminole Battalion" and "one company, Nail's Chickasaws and Choctaws".
Capt. Jonathan Nail (older brother of Adam) commanded the unlettered "Nail's Company" of the 1st Chickasaw Cavalry Battalion which was commanded by Lt. Col. Lemuel Reynolds. This battalion was composed of Chickasaw, Choctaw, and Texans (or frontier men) for service in the Chickasaw Nation. Nail was himself a Choctaw.

Phillips reported the Confederates were Seminole, Choctaw, and Texans. This is perhaps where the assumption that some of Bass' men were there comes from. Upon his return to Ft Gibson, Phillips mentions "...Col. Jumper's regiment, which consisted of the Chickasaw and Seminole battalions, but was broken to pieces in the late battle."

Per the ORs, Phillips raided westward through the Creek and Seminole country before consolidating his force at the mouth of Little River (Edward's, Little Rivertown, Old Fort Holmes) on the 11th. On the 13th, Willetts moves south and engages the Confederates at Middle Boggy in the Choctaw Nation, about 4 miles south-southwest of present Allen OK and only a few hundred yards east of the Chickasaw-Choctaw border. He camps there or nearby at Camp Kansas. Cooper reports on the 13th that Phillips is 45 miles from Boggy Depot. On the 14h, Phillips sends his infantry and train back to Little River and takes his mounted force 21 miles "southward" and establishes Camp Kagi in the Chickasaw Nation. Cooper reports Phillips is only 30 miles from Boggy Depot. From this point, Phillips sends two scouts of about 50 men each toward Ft Washita to try and get the Confederate to pursue and attack him. They don't, and Phillips returns to Little River . From there he takes his train direct to Ft Gibson and sends his forces northwest and north through the Creek and Seminole Nations before they return to Ft Gibson.

Ken