And certain individuals............

Maj. Gen. Joseph Hooker, who became commander of the Army 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 by John C. Babcock, who had worked for Allan Pinkerton and had made maps for George 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]

The most useful military intelligence of the American Civil War was probably provided to Union officers by slaves and smugglers.^[11] Intelligence provided by slaves and blacks were called black dispatches.^[1