Gary D. Bray,
You are right, this John C. Carter from Red River County is mentioned on 5 pages of my Appendix, and yes, I have him elected as a major of the 1st Regiment of the Red River Militia in July 1861 then again in April 1862. He served as a 1st Lt. in Ragsdale's Dragoons of Red River County. And yes, it makes sense that McCulloch should "retain both Major M.G. Settle of Lamar County and Major John C. Carter of Red River County."
This was an oversight on my part. Again thank you.