I haven't searched this board in quite sometime; I did just read
a message from "DOYLE" in Jan. 2010, about the Arkansas Garrison??, and he mentioned
Capt. McDuff Vance, in the 11th AR Co. A, that he was curious as to know about him.

I've just discovered Lt.Col. McDuff Vance's grave, received his mil. records from AR Hist.
Commission, and placed an order for him a military stone. He is bur. in
Oak Hill Cem. McAlester, Pittsburg Co. OK.
In the history I've read online about the 11th AR Inf. Reg., I didn't see
anything about Prisoners of War, but he was captured at "Island 10, on April 8, 1862. On April 22nd, was admitted to U.S.A. Post Hosp., Camp Chase, near Columbus, OH, and 'returned to duty/Prisoner of War, May 11, 1862. On May 16,1862 CSA Roll of Prisoners of War muster sheet, 'Remarks: Sent to Owensburg(sic?) Sept. 1, 1862.'
Don't know when he was released/traded, but he got paid from Oct-Dec. 1862. (from voucher).
He was in his Unit in 1863-4, but was again a "Prisoner of War, in 1865, and "...was surrendered by Lieut Gen. R. Travis, CSA, commanding said Department, to Maj Gen E.R. Canby, USA commanding Army and Division of West Mississippi, do hereby give my solemn 'parole of honor' that I will not hereafter serve in the Armies of the Confederate States.
Signed this 14 day of May, 1865."

McDuff (M.D.) Vance was promoted to "Lieut. Col. Nov. 9, 1863, by election, to take rank, Sept. 30, 1963. Delivered by Col. Pralfrey"
McDuff Vance was my grandfather's first cousin...they were born in MS, but moved to Arkansas, where McDuff served. He was later in Indian Territory (Oklahoma) before 1900, and with his son, ran a wholesale grocery business.
His memorial is on the link, "Find-a-Grave, for the above named State, County and City.