I agree with fyrffytr1 on this one , while "tin backs" did exist during the Civil War era . they were very scarce especially in the naval branches of the military. these motifs were very popular around the 1900's on many civilian articles of clothing .
Al , its still a nice button and I would still put in in any of my military displays because even though it may indeed be used for civilian , the design or motif is inspired by earlier type military buttons.
Dan