Subtitled “The Untold Story of Military Intelligence in the Civil War”, this book is a great exploration of the development of the methods by which the Union Army of the Potomac obtained information about the Southern opposing forces.
Like too many books, its focus is exclusively on the East, and virtually all before and during the Gettysburg campaign. The nearly two years after that until Appomattox, and everything west of the Shenandoah Valley is not a part of this study. Since this results in a 700 page, relatively small print tome, it is hard to argue with the decision, but it is a little disappointing.
The sources of military intelligence are varied – there is physical observation by your own forces, usually cavalry. There are reports of civilians, and spies sent out to gather information. There is also information gleaned from the interrogation of deserters and prisoners. There is the examination of captured papers and documents, even newspaper reports. Properly used, all of these can give a picture of the composition, location, and even movements and plans.
The Southern efforts are mentioned for the Eastern Theatre, but in general aside from scouting with Cavalry, their efforts were uncoordinated and bore little fruit. The North created several semi professional and fully professional organizations with the army, and in general did a better job all around.
There are several new bits of data to be learned:
- The estimates of enemy force that McClellan presented early in the war have been blamed on bad techniques by the amateur work of Pinkerton and his detectives. Actually, those reports were better estimates than McClellan gave to the government, and he knew that those were ‘worst case’ numbers. As time when on, Pinkerton tried to enlarge his estimates to fit McClellan’s, but then Mac raised those even more.
- During John Pope’s campaign, a spy delivered timely information that Lee was planning a move to trap his army, and Pope evaded the trap. The source was reported to be from a cavalry raid capture, but this was a bit of disinformation to protect future attempts to insert a scout into Lee’s army.
- The signal corps was a continual asset – they often intercepted Confederate unencyphered transmissions and even inserted false information for the Confederates to intercept.
- Hooker developed an excellent service that gave him perfect knowledge of the size and location of Lee’s army which he used to almost trap him at Chancellorsville. The fact that Hooker fumbled the chance after that was not due to bad information.
- In the lead up to Gettysburg, the information confirming a move north also came from a spy moving with the Army of Northern Virginia. Ironically, later an attempt by Lee to spread disinformation backfired. Deserters reported that Hill’s corps was marching North across the Potomac, but bad information had this as the trailing corps. The result was that Hooker crossed the river himself and stole a march on Lee. If Hooker had known that Longstreet had not crossed, he would have had to hold forces below the river to avoid a strike at Washington from the south.
- The final interesting tidbit was that the service was busy on the battlefield of Gettysburg finding the units of prisoners taken. By the end of July 2, they could report that every division of Lee’s Army had been heavily involved in fighting except for Pickett – which meant that Meade knew that he had far more fresh troops to call on during day three.
This is one of those ‘must read’ books for the Civil War buff. Now someone needs to expand this to the West and to the Late War in full. There are hints of interesting work of spies and scouts in the West — the news that Grierson’s raid had safely arrived at Baton Rouge from the Memphis area reached Memphis in a matter of hours – it must have been telegraphed across the state of Mississippi using Confederate telegraph lines!