Hi, Amanda. If you send your current email address to my email,
thaxtongenealogy@yahoo.com, we'll send you the new info we have: 1) reference to a 1/16/1865 appt as Provost Marshal in Ark., and 2) a short account by a troop member in 1901 that describes James and says he saw an announcement of his death. I'll also look to see if there are any Fort Riley records at the Family History Library here.
Karra