imgur.com/a/tZo2c
She told me that her grandmothers second husband had been a free man of the City of London. After finding the copy that her Gran left her (I've added at the bottom encase anyone was interested) I also found this loan bill inside the small leather sleeve. As a Brit I know very little of the American civil war but it seems to be dated to that period with a small sections about it being paid upon lifting of the blockade. I stupidly forgot to take a photo of the whole of the back but that's where all those "warrants" where What sort of this has my great-great-grandfather-in-law been investing in?
That is a form of currency- a note issued not by the Confederate States government or the State of South Carolina but by the Cotton Planters Loan Association. Or it appears to be- I'm no paper currency expert but I do know Confederate currency has been widely faked. Perhaps you should post this to /r/papermoney where collectors of such bills hang out. Like all banknotes of the time it could be redeemed in gold, but in this case that would have had to wait until the Union blockade was lifted and cotton could be exported again.
The back of it actually has nothing to do with the front- it appears to have been printed on scrap paper that was intended to be part of a bond issued by the Spartanburgh and Union Railroad Co. The warrants would be used to claim your half-yearly interest on your investment.
Your imgur link does not seem to be working.