Not a daguerreotype! Dags were obsolete by 1860, having been replaced by collodion-coated glass plate (an ambrotype) later by a variant, collodion on dark varnished iron plate (the tintype). Due to the style of the brass mat and the brass frame, this is positively at least late 1860's, maybe 1870's. To verify it is a tintype, your image package has a protective glass cover plate.; take a strong magnet, lay it on the cover glass, then turn the cased image upside down. I'll bet the magnet holds, indicating the attraction to the iron of the plate.
I agree this is civilian, probably 1870's, and a band. No cigar for being a military image, but still a fun piece of history!