I made some further inquiries with a view to establishing the identity of Rector Johnson, and it does indeed appear that his full name was MATTHEW RECTOR JOHNSON of Neosho, Missouri. This is the man who was Captain of Company D, Livingston's/Pickler's/Piercey's Battalion. For some reason, Johnson was apparently in charge of the battalion (or perhaps a detachment of it) during Price's Raid. In early December 1864, the battalion - now led by Major Andrew Jackson Piercey - reported for duty with Stand Watie's 1st Indian Brigade in the Indian Territory, where they remained until the end of he war. If you are able to piece together a picture of the battalion's activities during Price's Raid, I would be interested to know.