Thanks so much Jsff. That's just the kind of info I was looking for. I will send you an email, and wojld be happy to share whatever I've found. I guess we'll have to call them the "four flags" mortars or possibly five, but not six, since they never would have served under the British crown.
I got some interesting info regarding the armament of Ft. Clinch at the time of capture, from the Civil War Message Board, where I posted in the section for the State of Florida. These two Spanish mortars may well have been the two unmounted pieces found "beyond the railroad bridge" I think the report said. I've been unable to find specific reports of what the Navy picked up at the time, but the inscriptions and all their additional stampings for "Class..." and "Trophy No." tell that story well enough for now.
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