One of the first orders that Union Major General Joseph Hooker made after becoming the commander of the Army of the Potomac was on February 11th 1863, creating the Bureau of Military Information.
The Pinkerton National Detective Agency, run by Allan Pinkerton assumed responsibility for President Abraham Lincoln’s safety in 1861. Pinkerton also provided intelligence for Union General George B McClellan. General Winfield Scott hired Lafayette C Baker a detective for information. Lincoln himself paid a publisher; William A Lloyd to infiltrate the Confederacy and provide information. In all these cases though, these men were civilians.
When Union Major General Joseph Hooker became the commander of the Army of the Potomac, he ordered his deputy provost marshal Colonel George H Sharpe to create an intelligence unit. Sharpe received assistance from John C Babcock; a former Pinkerton employee and they established the Bureau of Military Information [the BMI] on February 11th 1863.
The BMI had about 70 field agents during the, 10 of whom were killed during the war. These and additional agents preformed interrogations, scanned confederate newspapers and captured documents for information that could be helpful to the Union war effort. Union General Ulysses S Grant kept BMI staff in his headquarters, so he would have the most recent information.
The BMI ceased to be once the Civil War came to an end in 1865.