Frank, if it is southern Mythology then it seems to be pretty well accepted as even the History Channel has done programs about Banks and the his obsession with the Red River.

The Treasury Department (U.S.) even establish customs houses on the Mississippi to ship cotton directly to Europe. Northern Cotton Speculators from St Louis followed right behind Porters federal fleet as it moved down the Mississppi and in some cases were even ahead of him. The O.R.'s are full of numerious accounts of the value of Cotton in the Mississippi valley war and the trade in cotton, even the sale of Contribands for Cotton by the Union army.

So if it is "Southern Mythology" it is based it "Union records".