I think the earliest daguerrotypes may have been invented in the 1830s. A few photos exist taken in the Mexican War. I have a photo of my great-great-great-grandfather with his second wife, taken sometime between 1853 and his death (about 1871). His first wife, my ancestor, died in 1852--but I sometimes see the photo of the second wife identified as the first wife.
My Revolutionary War ancestor died in 1822, before photography, but I run across a photo online identified as him--actually of his nephew who had the same first and last name.
I do have a daguerrotype of my great grandfather in his Union Army uniform. The image is on glass with a copper edging to cover the sharp edges.
My paternal grandmother was an active DAR and member of the Mayflower Society. She did most of the serious research for the family genealogy records.