Method of Transmitting Messages in Cipher
Under the system enforced by the War Department in 1864-5, the commanders of troops in the field were compelled to communicate with each other either in plain language which the enemy could read if a despatch fell into his hands, or else in a cipher which neither of the commanders nor any of their staff officers could decipher. They were made absolutely dependent upon the cipher-operators of the telegraph corps. Of course all this cipher correspondence between commanding generals was promptly transmitted to the War Department, so that the Secretary could know what was going on as well as anybody. Whatever may have been the object of this, perhaps not difficult to conjecture, its effect was to make rapid correspondence in cipher impossible when rapidity was most important and secrecy most necessary. In previous years I and one at least of my staff officers were always familiar with the cipher code, so that we could together, as a rule, quickly unravel a knotty telegram. Indeed, I once had to decipher a despatch to which I had no key, except I knew from internal evidence that it must be under the War Department code, though written in a different key. It was a despatch from Grant, who was then besieging Vicksburg. It had been sent to Memphis by steamer, and thence by telegraph to St. Louis, the place from which Grant’s army drew its supplies. A cipher despatch sent under the circumstances from Grant to me, who was not at that time under his command, must necessarily be of great importance. My staff officer at once informed me that it was in some key different from that we had in use. So I took the thing in hand myself, and went to work by the simplest possible process, but one sure to lead to the correct result in time—that is, to make all possible arrangements of the words until one was found that would convey a rational meaning. Commencing about 3 P. M., I reached the desired result at three in the morning. Early that day a steamer was on the way down the river with the supplies Grant wanted. I never told the general how he came to get his supplies so promptly, but I imagined I knew why he had telegraphed to me rather than to the quartermaster whose duty it was to furnish supplies for his army—and a most capable and efficient quartermaster he was. I had only a short time before voluntarily sent General Grant 5000 men, and I inferred that there was some connection between the incidents.
The immense change in the whole military situation which was produced in a few minutes at Franklin (for the contest there was in fact decided in that time, by the recovery of the breach in the line), and that by a battle which had not been contemplated by either General Thomas or myself (that is, on the south side of the Harpeth River, with that stream in the rear of the army), nor yet by General Hood until he saw the apparent opportunity to destroy his adversary; and the fact that that dangerous situation had been produced and the battle rendered necessary by slight accidents or mistakes which might easily have been foreseen or avoided, cannot, it seems to me, but produce in every thoughtful mind some reflection upon the influence exercised by what is called “accident” or “chance” in war. The “fortune of war” was, upon the whole, always in my favor, in spite of adverse accidents; yet I have always acted upon the principle that the highest duty of a commander is to anticipate and provide for every possible contingency of war, so as to eliminate what is called chance.