America’s Unknown Intelligence Czar

Under Burnside, the army of the Potomac’s “secret service” consisted of a single private.

Befitting the worldview of a civilian detective, Pinkerton sent what spies he did infiltrate behind enemy lines almost exclusively to Richmond, the enemy capital—”probably,” writes Edwin C. Fishel, author of The Secret War for the Union, “because a city could be penetrated much more readily than a field army’s headquarters.” Pinkerton’s spies in Richmond provided ample fodder for dramatic tales of derring-do published after the war, but they actually obtained little information of importance.

Worst of all, Pinkerton’s reports to McClellan almost always consisted of raw, undigested intelligence, without any context or analysis. This left to McClellan himself the crucial job of interpretation, and that was where the real mischief took place. Although Pinkerton has been ridiculed for years by historians for providing McClellan with grossly inflated estimates of Confederate troop strength, in fact this was but a symptom of the unprofessional way McClellan’s whole intelligence system was organized. Initially, Pinkerton actually put together a surprisingly accurate picture of the Confederate “order of battle"—its organization into corps, divisions, brigades, and regiments. But before he could take the next step and use this organizational chart to build up an estimate of Robert E. Lee’s total troop strength, McClellan was already whining to Washington that he needed more men before he could attack the Rebel army, claiming that Lee outnumbered his forces by three to one.

When Pinkerton reported that the Confederates numbered 98,400—double the number now known to be the actual figure, but still far less than the 170,000 McClellan had claimed—McClellan started leaning on him to adjust his figures, “to be sure and cover the entire number of the Enemy.” And Pinkerton did his best to defer to his commander’s wishes.

Under a commander more supportive of objective intelligence analysis, Pinkerton would almost surely have produced a much more accurate estimate. But as Fishel observes, the much-maligned detective “worked for a general who did not really use intelligence except to justify his own dislike of fighting.”

When McClellan was relieved of his command, Pinkerton folded his shop, taking all his files and his team of civilian detectives with him. Under McClellan’s successor, Burnside, the remnants of the Army of the Potomac’s “secret service” consisted of a single private. Hooker, when he came in, was determined to remedy that at once. He ordered his provost marshal general, Marsena Patrick, to “organize and perfect a system for collecting information as speedily as possible.”

It was a tall order for the provost marshal general, whose major job was arresting deserters. Patrick complained in his diary: “I am trying to make up a system of Secret Service, but find it hard to organize where there is so little good material. . . . I do not fancy the class of men & think they do not fancy me.” But a few days later Patrick recorded a stroke of luck; he had had a “long conversation” with Colonel Sharpe about the job of chief of the “Secret Service Department.” Patrick noted that Sharpe “appears well, & I think would be a pleasant man to be associated with.”

Patrick had been a brigade commander in a division that included Sharpe’s regiment and so was at least generally acquainted with him. Besides being a lawyer, a point Patrick commented on favorably, Sharpe had some powerful political connections that no doubt recommended him. He had been active in local Republican politics in upstate New York, and his law partner was a U.S. congressman well connected with Secretary of State William Seward.

Sharpe was reluctant to leave his regiment but in the end was talked into taking the headquarters assignment. He immediately threw himself into the task, organizing the “Secret Service Department” into an efficient, businesslike organization, reflected in the new low-key name it soon acquired, the Bureau of Military Information (BMI). Almost immediately there began to flow into Hooker’s headquarters a steady stream of understated but confident reports on Lee’s army, its movements, disposition, and intentions. Many of them in Sharpe’s own hurried handwriting, others filling hundreds upon hundreds of message blanks from the U.S. Military Telegraph service, they today fill box upon box in the National Archives, and they cover everything from reports of individual interrogations of Confederate prisoners of war to comprehensive assessments of the enemy’s organization and maps reconstructing the locations of enemy units and fortifications.