Tactical or battlefield intelligence became vital to both sides in the field during theAmerican Civil War. Units of spies and scouts reported directly to the commanders of armies in the field, providing details on troop movements and strengths. The distinction between spies and scouts was one that had life-or-death consequences: if a suspect was seized while in disguise and not in his army's uniform, he was often sentenced to be hanged. A spy named Will Talbot, a member of the35th Battalion, Virginia Cavalry, was left behind inGettysburg after his battalion had passed through the borough on June 26–27, 1863. He was captured, taken toEmmitsburg, Maryland, and executed on orders of Brig. Gen.John Buford.[1]
Intelligence-gathering for the Confederates was focused onAlexandria, Virginia, and the surrounding area.
Thomas Jordan created a network of agents that includedRose O'Neal Greenhow.[2][3] Greenhow delivered reports to Jordan via the “Secret Line,” the name for the system used to get letters, intelligence reports, and other documents across thePotomac andRappahannock rivers to Confederate officials.[citation needed]
The Confederacy's Signal Corps was devoted primarily to communications and intercepts, but it also included a covert agency called theConfederate Secret Service Bureau, which ran espionage and counter-espionage operations in the North, including two networks in Washington.[4]
The Union's intelligence-gathering initiatives were decentralized.Allan Pinkerton worked for Maj. Gen.George B. McClellan and created theUnited States Secret Service.[4]Lafayette C. Baker conducted intelligence and security work for Lieutenant GeneralWinfield Scott, commander-in-chief of the U.S. Army. PresidentAbraham Lincoln hiredWilliam Alvin Lloyd to spy in the South and report to Lincoln directly.[4]
As abrigadier general in Missouri,Ulysses S. Grant was ordered by Maj. Gen.John C. Frémont to start an intelligence organization.[4] Grant came to understand the power of intelligence and later made Brig. Gen.Grenville M. Dodge the head of his intelligence operations that covered an area fromMississippi toGeorgia with as many as one hundred secret agents.[4]
Maj. Gen.Joseph Hooker, who became commander of theArmy of the Potomac in January 1863, ordered his deputy provost marshal, Col.George H. Sharpe, to create a unit to gather intelligence. Sharpe set up what he called the Bureau of Military Information and was aided byJohn C. Babcock, who had worked forAllan Pinkerton and had made maps forGeorge B. McClellan. Sharpe's bureau produced reports based on information collected from agents, prisoners of war, refugees, Southern newspapers, documents retrieved from battlefield corpses, and other sources. When Grant began his siege of Petersburg in June 1864, Sharpe had become Grant's intelligence chief.[4]
African American slaves and free persons provided valuable intelligence supporting Union military operations, often exploiting their ability to move across lines without attracting attention. African American Civil War Intelligence Contributions (formerly known asBlack Dispatches. contributed significantly to the Union's ultimate victory.[13]
