An attractive and interesting piece, and wouldn't it be something to really learn its history?
For what it's worth--and as alluring as it is to make the connection--I'm afraid I would skip the idea of this coin as a Civil War piece (except perhaps as an ID tag, which doesn't seem likely either). Foreign coins were demonetized in the U.S. in 1857 (the process to be completed by 1859), and so this coin had lost whatever officially-sanctioned utility it might have had in the U.S. by the time of the Civil War.
But metal was money, of course, so?
Had it shown itself it likely would have disappeared right away, and not circulated. And if it was an advertising piece of some sort, which seems more likely--and if it was an American or American concern being advertised--to use a silver piece for advertising purposes during the Civil War seems like very bad business indeed.

v.