Editing Allan Pinkerton (section)

==American Civil War==
[[File:PinkertonLincolnMcClernand.jpg|thumb|right|Pinkerton (left) with [[Abraham Lincoln]] and [[John Alexander McClernand|Major General John A. McClernand]]]]

When the [[American Civil War|Civil War]] began, Pinkerton served as head of the Union Intelligence Service during the first two years, heading off an alleged [[Baltimore Plot|assassination plot]] in [[Baltimore, Maryland]] while guarding [[Abraham Lincoln]] on his way to Washington, D.C., as well as providing estimates of [[Confederate States of America|Confederate]] troop numbers to General [[George B. McClellan]] when he commanded the [[Army of the Potomac]]. His agents often worked undercover as Confederate soldiers and sympathizers to gather military intelligence. Pinkerton himself served on several undercover missions as a Confederate soldier using the alias Major E.J. Allen.  He worked across the Deep South in the summer of 1861, focusing on fortifications and Confederate plans. He was found out in Memphis and barely escaped with his life. This counterintelligence work done by Pinkerton and his agents is comparable to the work done by today's [[United States Army Counterintelligence|U.S. Army Counterintelligence Special Agents]] in which Pinkerton's agency is considered an early predecessor.<ref>{{cite thesis|last=Stockham|first=Braden|title=The Expanded Application of Forensic Science and Law Enforcement Methodologies in Army Counterintelligence|year=2017|publisher=Defense Technical Information Center|location=Fort Belvoir, Virginia|page=6|chapter=Chapter 2: Literature Review: Historical Background}}</ref> He was succeeded as Intelligence Service chief by [[Lafayette Baker]]; the Intelligence Service was the predecessor of the [[United States Secret Service|U.S. Secret Service]]. His work led to the establishment of the Federal secret service.<ref>{{cite encyclopedia |editor-last=Hart |editor-first=James D. |editor2-last=Leininger |editor2-first=Philip W.| name-list-style= and |encyclopedia=The Oxford Companion to American Literature |title=Pinkerton, Allan |year=2004 |publisher=Oxford |isbn=978-0195065480 |url-access=registration |url=https://archive.org/details/oxfordcompanionthart }}</ref>

Military historians have been strongly critical of the intelligence Pinkerton provided for the Union Army, which for the most part was undigested raw data.<ref name=sears104 /> In the view of [[T. Harry Williams]], Pinkerton's work was "the poorest intelligence service any general ever had."<ref>[[T. Harry Williams|Williams, T. Harry]] (2000) [1952] ''Lincoln and His Generals''. New York: Gramercy Books. p. 50. {{isbn|978-0-517-16237-8}}</ref>  Pinkerton's estimates of Rebel troop numbers, derived from his credulous interrogations of Confederate prisoners, deserters, refugees, escaped slaves ("contrabands"), and civilians unused to counting large bodies of men, badly exaggerated the size of those formations, sometimes almost doubling their actual strength.  Pinkerton's numbers caused McClellan to consistently believe that he was drastically outnumbered by the Confederate forces he faced.  McClellan's action in the face of what he believed were overwhelming odds were unduly cautious, causing him to avoid offensive actions almost completely in favor of [[siege warfare]] and taking a defensive posture.  This led to his retreat in the [[Peninsula Campaign]], his failure to crush [[Robert E. Lee]]'s [[Army of Northern Virginia]] at the [[Battle of Antietam]], and his unnecessary delay in carrying out his orders to pursue Lee's army as they retreated from their invasion of Maryland back into Virginia.  These actions were all based on McClellan's firm trust of Pinkerton's reports, although the problem was compounded by the intelligence-gathering ineptitude of Brigadier General [[Alfred Pleasonton]], McClellan's head cavalryman and his alternate source of enemy troop information when Pinkerton did not have agents in place.<ref>[[Stephen W. Sears|Sears, Stephen]] (1988) ''George B. McClellan: The Young Napoleon'' New York: Da Capo Press. pp. 107–110, 274. {{isbn|978-03068091-32}}</ref><ref>Murfin, James V. (2004) [1965] ''The Gleam of Bayonets'' Baton Rouge, Louisiana: Louisiana State University Press. pp. 40, 45, 50, 54–55, 125. {{isbn|978-0-8071-3020-9}}</ref>{{efn|McClellan was so committed to believing Pinkerton's numbers, that even years later, at a time when those numbers were well known to have been widely inaccurate, he used them in writing his memoirs. McClellan had employed Pinkerton as a detective when he was an executive of the Illinois Central railroad, and his service to McClellan during the war was as a civilian employee working from the provost marshall's office, not as a member of the Union Army.  To some extent, McClellan himself was responsible for the exaggerated numbers, as he had instructed Pinkerton to overestimate in order to account for troops not yet found.  Pinkerton's sycophancy undoubtedly also contributed, as he provided for his boss the kind of numbers that it was obvious McClellan expected to receive. See Murfin (2004) [1965], Sears (1988) and Sears (2017), p. 84}}

On the other hand, Edwin C. Fishel in ''The Secret War for the Union'' and James Mackay in ''Allan Pinkerton: The First Private Eye'' argue that the troop strength figures which Pinkerton passed on to McClellan were relatively accurate, and that McClellan himself held primary responsibility for inflating those numbers to wildly unrealistic levels.<ref>Fishel, Edwin C. (1996) ''The Secret War for the Union: The Untold Story of Military Intelligence in the Civil War''. Boston: Mariner Books. pp. 103–129. {{isbn|0-395-90136-7}}</ref><ref>Mackay (1997), pp. 8–9</ref>

[[File:Pinkerton allan late harpers.jpg|thumb|left|Portrait of Allan Pinkerton from ''Harper's Weekly'', 1884]]