Corrine, you probably came across this family researcher's entry in your search for Marcus J. Truss.

Name: Marcus J. Truss
Sex: M
Birth: 1836 in Alabama
Death: 8 APR 1862 in Civil War of Brain Fever
Military Service: 9th Alabama Battalion CSA

I didn't find any records for this soldier in the 9th. Alabama Battalion, but did find a Private M. D. Truss in Company K, 18th. Alabama Infantry Regiment. This soldier enlisted in Ashville, AL and died in camp near Corinth on 8 April 1862.

You can read more about the 9th. Alabama Battalion (See 58th. AL Regt.) and 18th. AL Regt. at this site, they were a part of this brigade.
http://ehistory.osu.edu/USCW/features/regimental/alabama/confederate/clayton.cfm

I would also suggest seeking information on the Alabama Message Board.

Hope this helps and good luck with your research.