Several people have been looking for a map of DeVall's Bluff showing the Union installations there. The Arkansas History Commission has a copy but I just found a National Archives site with high res scans of their Civil Works map file with the full color DeVall's Bluff map. It is in two pieces.

http://narademo.umiacs.umd.edu/cgi-bin/isadg/viewitem.pl?item=105802

Enjoy!