Bob, Major Balch's CSR says he was taken prisoner in Memphis in 1863, and suggests that he deserted. He was listed as age 35 at the time--which would eliminate the "other" Robert M. (McClellan) Balch of Madison Co., AL (1844-98) who has a VA headstone with the service record of the major.

An 1883 TN Supreme Court case seems to confirm the 1871 date the Balch book has. In it a R. M. Balch owns land in Crittenden County in 1871, and is dead by 1876. I couldn't find a death notice in the Memphis Appeal.