Intriguing and tantalizing as William B Feis'2002 book Grant's Secret Service: the Intelligence War from Belmont to Appomattox is, ultimately it fails to live up to its promise, which perhaps is less the fault of Feis than a failure of the supporting evidence and stories we most want to know to survive the intervening fourteen decades.
Feis successfully grafts on a new dimension to the story of US Grant at war, providing the names of certain spies and scouts and networks of the same, providing intermittent streams of intelligence, accurate and flawed, in Grant's general direction. By itself this is useful and often fascinating information, as American Civil War history has a way of gravitating to decisions made by generals which are presented in a vacuum: here are identified some of the voices of those who contributed to those decisions in the higher echelons. Unfortunately, we get relatively little sense of the personalities of these clandestine figures, and much less do we hear what their whispered voices actually said. Feis makes known their ghostly presence in the periphery and in the lonely, dangerous wilderness beyond, but the significance of the contribution of their intelligence remains elusive.
Of course it's a matter of good spy- and scout-craft to leave footprints as light as possible. Feis paints a broad picture of some of Grant's sources of intelligence, but it's doubtful we'll ever learn what those reports said and what importance they actually had in influencing Grant's decisions and choices. And as Feis points out again and again, Grant as a rule preferred holding onto the initiative to relying on military intelligence.
Discussion of Grenville Dodge's network of scouts centered at Corinth was most illuminating, as was the perception of Jubal Early's raid on Washington as an intelligence failure: the linking of the last Shenandoah Valley campaign with the Petersburg campaign as an integrated strategy by Lee was enlightening.
At the ends of most chapters Feis presents a few paragraphs of summary that usually are intended to show how intelligence influenced individual battles or campaigns. As often as not I felt opposite conclusions might as well have been drawn from the same evidence that had been presented: that is to say, he seemed to be cherry-picking his conclusions to fit his thesis that intelligence operations were more central to Grant's decision-making than we might have supposed. I will say the maps in this book are truly superb. Curiously, a number of editorial errors are present: use of a wrong word, improper punctuation of "its", etc. Nevertheless, this book is a quick read and a real page-turner: it's just that it doesn't quite deliver the goods we most want. (Even the Corinth interval comes somewhat to life in the material about Dodge.) This may be the best book that could be written about this subject. One wishes that a more illuminating book had been possible, and hopes against hope that in the future more solid evidence will be discovered that provides clearer insight into the personalities of the spies in the shadows, and the specific contributions of military intelligence in Grant's military career.