In a previous post, we looked at how Abraham Lincoln utilized the telegraph during the Civil War to supervise his generals in the field and gather intelligence — sometimes by scanning telegrams intended for other Washington recipients. But in addition to working closely with Lincoln, the War Department's team of telegraph operators — who were based at the present-day location of the Eisenhower Executive Office Building, next door to the White House — also were pressed into service to perform another critical function in the war effort. They also worked as cryptographers, encoding sensitive communications for the Union side, and as codebreakers, deciphering intercepted letters sent by Confederate officials and spies.
In an age when the federal government and the national security establishment was vastly smaller than it is today, David Homer Bates and three other operators — Thomas T. Eckert, Charles A. Tinker, and Albert B. Chandler — functioned as the 19th Century equivalent of the Fort Meade, Md.-based National Security Agency, which has an estimated 30,000 to 40,000 employees and an arsenal of supercomputers and other gadgetry at its disposal.