Your Enfield is most likely a Pattern 1853, Third Model, made in Birmingham - the most common type imported by both sides in the WBTS. Other markings may reveal more info (gunmaker, parts makers, etc.).

I would be very skeptical of the C.S.A. marking - in my experience, most such markings are not genuine. The Confederacy marked few Enfields, and I can't recall that I have ever seen a bona fide "CSA" marking on an Enfield.

Geoff Walden