Question

Clinton Armstrong disappeared after enlisting CSA

Answer 1

Could you please edit your question and add what country, dates, and what CSA means, thanks

Comments

CSA – Confederate States Army

Answer 2

To get the discussion going, there is a Clinton C. Armstrong. who enlisted on October 2, 1862, in Hawkins County, Tennessee in the 39th Mounted Infantry under Col. W.M. Bradford.  He was captured and paroled at Vicksburg, Mississippi on July 10, 1863, after agreeing not to take up arms against the United States again. https://www.fold3.com/image/78162800

Comments

Not much info in the question posted or even a Wikitree profile but to build upon your answer. I believe this findagrave is Clinton C. Armstrong https://www.findagrave.com/memorial/93395449/clinton-charles-armstrong