Also get a better pic of that chain if you can.. lay it out best you can then take a pic of it! think I have a few ideas what that may be
I was thinking it could be a Cavalry trace chain that the confederates used. I do not know what kind of camp you were hunting union or confederate. The union had things marked all the time like in the photo while the confederates would have to use stuff that was not marked or machine made. This could be a confederate cavalry chain. Will have too look later @ the books and research it.
.......thats newer chain,and does look like a foot hold trap chain and ring....
http://marketplace.veer.com/stock-photo/rusty-old-leg-hold-trap-3835407
http://compare.ebay.com/like/370712994584?var=lv<yp=AllFixedPriceItemTypes&var=sbar