It was used, tethered, to observe for artillery and to keep track of troop movements.
I know the Confederates attempted to use submarines.
Not only attempted, but sank the first enemy vessel sunk in battle with one. That the Hunley sank on the way home only kept them from doing it again.
Kind of gives a new twist to “the South shall rise again” doesn’t it?
Yep!
The Hunley killed far more confederates than it did yankees.