Could not his position as a Volunteer aide be an unofficial, unpaid position?

Card No. 5 in his file with Lenoir’s Independent Company, Alabama Cavalry, notes

“Vol. ADC to Gen Cantey”

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James Cantey was appointed a brigadier general to rank from January 8, 1863. Cantey was detached[3] and sent to Mobile, Alabama from January 1863 through April 1864,[4]

http://en.wikipedia.org/wiki/James_Cantey

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Gen. James Cantey, Commanded the Garrison at Mobile,
The Photographic History of the Civil War, Vol. X