Perhaps the original entry as 6th Missouri Infantry was in error and should have read Cavalry and the
12th (Shank's) Missouri eventually morphed into the 6th Mo. Cavalry?
After Hays fell at
Xewtonia, Beal Green
Jeans was made colonel
of the regiment and
Shanks became major.
Jeans was afterwards
furloughed in Arkan-
sas, and due to great
losses this regiment
was reorganized under
Charles Gilkey as col-
onel. Gilkey lost his
life fighting gunboats
on the White River and
his ranks were deci-
mated. The regiment was newly recruited and became known
as the 6th Missouri Cavalry, with David Shanks as colonel,
ill Shelby's Brigade.
https://archive.org/stream/confederateveter22conf/confederateveter22conf_djvu.txt