So you don't consider the sunken blockade runner "Modern Greece" filled with ordnance and destined for the rebels a battlefield. How about all the shells from Fort Fisher lying on the ocean floor?? It is just as much a battlefield as any on land. We don't know how many of these shells were salvaged by the C.S. after it sunk.
What we do know is one box of 10 projectiles was recovered from its water grave and carried ashore, which is no different than digging one up on land. However, that being said, you are entitled to you opinion, and if you are correct in your assumptions, then I wasted my time gathered this documentation.
Lastly, please define battlefield!
Kind Regards,
John