By 1863 the Union army had established a printing department for its Army of the Potomac, undoubtedly a consequence directly related to the invention and sale of portable printing presses. The department retained more than ten printers from several Union states until the end of the war. At least three portable presses had been purchased for the unit by that year, along with some six portable type chests.
Open spread from the Pictorial Battles of the Civil War . . . , Benjamin LaBree, Editor (New York: The Sherman Publishing Company, 1885)
Union telegram requesting new army press, 1863
This military telegram of 1863 from Lt. Charles A. Brown, Chief of the Printing Department, Union Army of the Potomac, to the Philadelphia foundry L. Johnson & Co., requests an “army press,” size 10x14, with other materials.
Portable presses invented, advertised, and sold during the war were generally named “army” presses, particularly the Adams Cottage and the Cincinnati Army printing presses.
The Cooley Cabinet Printing Office was the only portable press, however, advertising the same 10x14 size printing bed requested by Lieutenant Brown. Some months earlier, the then-commander of the Army of the Potomac, General McClellan, had been listed as having purchased two complete Cooley Offices.
Type Chest, Army of the Potomac
Army of the Potomac Printing Department
After concern about his being mustered out of his unit in 1863 and leaving the Printing Department, it was arranged that he be honorably discharged from the Sixteenth Infantry Volunteers as of 1862 in order to be able to accept a commission as second lieutenant in the Army of the Potomac and continue as head and superintendent of the department. Charles Brown, along with the equipment from his department, was detailed to a government building in Washington before the end of the war. Brown was relieved of duty in April 1865.