From the start of the 1864 campaigns, the Federal signal teams, in all theaters, demonstrated the ability to intercept and decode Confederate messages sent by wig-wag. While I’ve focused on efforts at Charleston, similar activities in Georgia and Virginia show the Federal signaleers were quite adept at what we would call today Signals Intelligence – SIGINT.
But the nature of the intelligence gathering disciplines is one of move and counter-move. In September, 1864, information reached Major-General Samuel Jones revealing the successful Federal SIGINT efforts. On September 24, Jones communicated this to General Samuel Cooper, Confederate Adjutant and Inspector General, in Richmond:
A returned prisoner reports that the enemy have read all our signals. This was learned from a Yankee operator in Florida by an intelligent sergeant, who is now a prisoner.
This information apparently came from one of five privates exchanged in Charleston on September 23. Hold on to that thought for the moment.
Cooper passed this to the Confederate Signal Bureau for comment. But the Confederate signaleers knew well the Federal practice and had taken measures, at least in the vicinity of Richmond, to counter the code breakers. Captain William N. Barker responded on September 27:
The within statement had been anticipated by Major [James F.] Milligan and myself. The officers of the corps are instructed to change daily the “key letter” in signaling important messages. The inclosed letter will show how, for strategic purposes, we sometimes allow the enemy to read our dispatches while we read his.
The referenced statement was a confidential message from Milligan to Barker, passed a month earlier on August 27:
For strategic purposes we permit the enemy to read our signals by order of General Beauregard. We read theirs with ease and facility, having discovered their system of contracting, which is the omission of vowels in short words–for example, crs for cars, ws for was, and the first and last letters of short words, thus–tn for train, me for message, the context always developing the word.
I have been working on an alphabet, and can safely say I have at last succeeded in making up one which will defy their most rigid scrutiny. When the proper time comes I will introduce it. On the James River all important messages are sent by key, letter changed daily. Come over, you can spare the time, and under present circumstances I cannot, or I would come to you. Signals for strategy work to perfection, thanks to the mighty brain of the matchless Beauregard.
Ah! The “mighty brain of the matchless Beauregard“!
Milligan’s response offers a rare indication that the Confederates were doing the same to the Federal signal codes. There is also an element of “tradecraft” at play, with the Confederates deliberately allowing the Federals to read messages, “for strategic purposes.” The intent, perhaps, to introduce a system that would defy Federal efforts at a time when introduction would make the greatest impact on operations.
Recall that General P.G.T. Beauregard offered input to these code systems during the war. Earlier in the war he used simple cypher strings to encrypt messages. The messages in August-September 1864 indicate he remained very active in the development of encryption and signal techniques. I cannot find specifics as to the new system Milligan references. But I suspect it involved something more than the “code wheel” often associated with Civil War signals:
This particular device was used in North Carolina by Captain George C. Bain, received from Barker. It is presently in the collection of the Missouri History Museum. “On each of its 15 pages are two ribbons of alphabetized tape, one fixed and one adjustable, which could be manipulated to decipher, and possibly encipher, coded messages.” As the means of use offered is a matter of some conjecture, we cannot say if this was significantly different or more advanced than the Myer Disk.
But… let’s go back to where Jones got this information. At the same time he sent word to Richmond about this development, he offered a separate message discussing Federal troop dispositions outside Charleston:
A very intelligent private of our service, an exchanged prisoner, who arrived here yesterday from Hilton Head, informs me that Major-General Foster has recently received comparatively large re-enforcements of white troops; that 2,500 arrived from New York on one day, and others, he does not know how many, had previously arrived. He states that the enemy is now constructing a railroad from Beaufort to Port Royal Ferry, and they speak very freely of their purpose of making an attack, at no distant day, by land on this city.
So… how many “intelligent privates” did Foster add to the group exchanged on September 23, 1864? And were these hand selected and “fed” individuals with the purpose of providing Jones certain information “for strategic purposes”? More tradecraft at play, perhaps?
(Citations from OR, Series I, Volume 35, Part II, Serial 66, pages 626-7.)