[DOC] [TLE] Spying in the Civil War - American Civil War - HISTORY.com [PAR] General George B. McClellan hired the prominent Chicago detective Allan 
Pinkerton to set up the first Union espionage organization in mid-1861. ... 
Confederate Signal Corps and Secret Service Bureau ... Among the most famous 
were John Singleton Mosby, known as the Gray Ghost, who led guerrilla 
warfare in western... [DOC] [TLE] The Federal Secret Service - Signal Corps Association 1860 ~ 1865 [PAR] As the head of his famous detective agency, he had been known by General ... as 
the head of "Little Mac's" secret service, and remained until McClellan himself 
retired ... and secret societies in the most loyal parts of the Union were aiding the 
new .... Henceforth, important arrests were made under the direction of the 
military... [DOC] [TLE] Espionage In The Civil War [PAR] Dec 15, 2002 ... By the outbreak of the war, neither the Union nor the Confederacy had ... first 
organized secret-service bureau, formed in 1862 as a part of the CSA Signal 
Corps. ... by Allan Pinkerton, founder of the famous Chicago detective agency. ... 
In 1862, as secret-service chief for McClellan's Army of the Potomac,... [DOC] [TLE] Allan Pinkerton - Wikipedia [PAR] Allan J. Pinkerton (25 August 1819  1 July 1884) was a Scottish American 
detective and spy, ... Following Pinkerton's service with the Union Army, he 
continued his pursuit of train robbers, including the Reno ... Allan Pinkerton was 
so famous that for decades after his death, his surname was a slang term for a 
private eye. [DOC] [TLE] George B. McClellan - Wikipedia [PAR] George Brinton McClellan (December 3, 1826  October 29, 1885) was an 
American soldier, ... McClellan organized and led the Union's army in the 
Peninsula Campaign ..... by the overblown enemy strength estimates of his secret 
service chief, detective ..... Under the pressure of his ultimate soldier's 
responsibility, the will to... [DOC] [TLE] The Union's Spy Game - The New York Times [PAR] Aug 15, 2011 ... The Union rapidly, but disjointedly, tries to build an intelligence operation. ... 
Chicago police force in 1850 to start his own detective agency in Chicago. ... It 
was Pinkerton, even as he led the Secret Service for McClellan, who... [DOC] [TLE] Intelligence in the Civil War (PDF) - NC Museum of History [PAR] Even today, the identities of many spies remain secret. Henry Thomas ... als 
rather than for the Union Army itself. But here .... founder of the Pinkerton National 
Detective Agency. ... to set up a military intelligence service for McClellan's ... 
headed for McClellan's head- .... bureau, a part of the Confederate War 
Department in. [DOC] [TLE] WashingtonPost.com: The Secret War for the Union: The Untold ... [PAR] However, "secret service" referred not only to the work now known as ... 
Lieutenant George B. McClellan, engineer officers and future commanders of 
opposing armies, ... Enemy newspapers would be useful; they would be acquired 
as part of the .... detective-agency chief who had headed one of the Baltimore 
investigations. [DOC] [TLE] Espionage - Essential Civil War Curriculum [PAR] Espionage was not a crime under the civilian laws of either the United States or 
the ... from secret service funds administered by the Union and Confederate 
War ... organization by turning to Allen Pinkerton, head of a famous private 
detective ... On November 7, 1862, Lincoln relieved George McClellan from 
command of... [DOC] [TLE] Allan Pinkerton - About Famous People [PAR] As one who was assigned to assist the Union as a detective/spy, Pinkerton ... As 
the head of his detective agency, he took an assignment to guard ... Federal 
Secret Service, as well as conduct intelligence reports for McClellan when ... 
Consequently, in one report to McClellan, Allan Pinkerton, who signed reports 
under his... [DOC] [TLE] The Federal Secret service [PAR] After Pinkerton left the army, the whole secret-service department was ... 
Southern cause within the existing Union were well understood and under 
control. ... the imagination is apt to enwrap the

Question: This famous detective headed the Union secret service under McClellan
Answer: Pinkerton