Robert Heinlein to Ted Sturgeon, 11 Feb, 1955:"Story about two countries fighting not with men, not with robots, but with mutated-animal soldiers. Fighter-pilot cats (all the gadgetry automatic, but the piloting done by the supercat), Rhino tanks, ape paratroopers, sea lion "frogmen" etc."Full text is at http://www.lettersofnote.com/2012/10/help-from-heinlein.html As best I can recall, Mr. Heinlein's Door Into Summer was the first sf novel to ever consider CAD.