Here's what I have directly from the papers in Henry Smalley's military file in the National Archives. Seems a shame that after this careful record keeping Henry may be lying in an unmarked or unknown soldier's grave.
Henry Smalley volunteered for one year of service on February 17, 1865, in Bunkerhill, Ingham County. Mustered in February 26, 1865, Jackson MI by Capt. Berry. Joined company March 6, 1865.
Henry Smalley was admitted to the General Hospital in DeVall's Bluff, Arkansas (also referred to as the post hospital in another paper) on April 4, 1865.
Record of Death and Interment:
Name and number of person interred: Henry B. Smalley 98 (not sure where the "B" came from, not on his enlistment record)
Number and locality of the grave: Row 7 Grave 19
Hospital number of the deceased: 685
Regiment, rank, and company: Private Co. G 12th Mich. Inf.
Residence before enlistement: Bunkerhill Ingham County Mich.
Conjugal condition and if married residence of widow: Married, Bunkerhill Ingham County Mich
Cause of death: Erysipelas (other records in file describe as typhoid fever)
Age of the deceased: 37 years
Nativity: State of New York (Friendship, NY per enlistment record)
Date of death and burial: April 5th and 6th 1865
[A duplicate of this Record has been forwarded to the Sexton, and another remains at this Hospital]
To: Adjt General USA Washington DC
Sir: It becomes my duty to inform you that the person above described died at this Hospital as herein stated; and that it is desired his remains should be interred with the usual military honors.
Respectfully, Gen A. (Munink? can't make out signature) Asst Surgeon US Army Vols M Inf
USA General Military Hospital Devall's Bluff Arkansas
This copy of Record is to be transmitted to the Adjutant General at Washington immediately after the place of burial and the number of the grave have been ascertained and registered. The above notification is to remain attached.