24 December 1997
Excerpted from: Codes and Ciphers: An A to Z of Covert Communication, from the Clay Tablet to the Microdot, Fred B. Wrixon, 1992, paper. ISBN 0-13-277047-4, pp. 136- 38. [Note: Phrases capitalized indicate other topics described in the book.]
Myer, Albert (1829-1880), U S. Army surgeon and cryptographer. To finance his medical studies, Myer worked as an operator for the New York, Albany, and Buffalo Telegraph Company. After entering the army, he developed a visual signaling method in 1856 and called it flag telegraphy. (Two British officers, Sir Francis Bolton and Vice Adm. Philip Colomb, independently developed a similar system at about the same time.) Though it was approved for use in 1860, the year Myer became chief signal officer, the system was not fully appreciated until the outbreak of the U.S. CIVIL WAR in 1861. Myer's technique then came to be known as "wigwag," from the motions of its hand-held flags or disks for daytime signaling and torches or lanterns for sending messages at night.
In this code, alphabet letters were equated with three positions of the flag, disk, or torch. The flags measured two, four, or six feet square and were generally either red or black banners with white square centers or white banners with red square centers. The disks were 12 to 18 inches in diameter and were made of metal or wood frames with canvas surfaces. Somewhat easier to handle than the flags, they provided a different method for daylight communications. Each torch was a metal cannister filled with a flammable liquid attached to a staff. A second "foot torch" was placed on the ground before the signalman as a fixed point of reference, making it easier for the recipient to follow the torch's movements.
Each letter consisted of a combination of three basic motions. All began with the flagman holding his device vertically and motionless above his head. The first motion was initiated by bringing the device downward on the signalman's right side and then quickly returning it to its upright position. Motion number 2 involved bringing the device down on the left side and then returning it to the starting position. The third motion required lowering the device in front of the signalman, then restoring it to its vertical position.
The chart below indicates how letters and directions were conveyed. For example, a (112) would be signaled by motion 1, motion 1, and motion 2 in rapid succession. The periods signified a written pause in a sequence of movements. In action, this was also a pause, unless concluding the message.
a--112 h--312 o--223 v--222 b--121 i--213 p--313 w--311 c--211 j--232 q--131 x--321 d--212 k--323 r--331 y--111 e--221 l--231 s--332 z--113 f--122 m--132 t--133 g--123 n--322 u--233
MYER'S SIGNAL DIRECTIONS
3--End of a word 33--End of a sentence 333--End of a message 22.214.171.124--Signal of assent: "I understand," or general affirmative 126.96.36.1993--Cease signaling 188.8.131.52--Repeat 184.108.40.206--Move a little to the right 220.127.116.11--Move a little to the left 212121.3--Error
The method was first applied in combat by the Confederacy. A former Myer trainee, one Lt. Alexander, sent flag signals at Bull Run to warn the South's Gen. Beauregard of a Union flanking movement.
Union forces successfully used flag signals in September 1862, when Gen. Burnside was alerted to an attack by Stonewall Jackson's cavalry at the Battle of Antietam in Maryland. But at Chancellorsville, Maj. Gen. Joseph Hooker met disaster at the hands of Robert E. Lee in May 1863 due in part to very poor command links with his troops.
Two months later, the pivotal Union victory at Gettysburg, Pennsylvania, was directly influenced by signalmen who scaled the strategic heights of Little Round Top. Their presence is credited with delaying an early Confederate assault there, the failure of which affected the tactics of the entire battle.
Another Union success, Adm. David Farragut's naval victory at Mobile Bay, Alabama, in August 1864, benefited from signals exchanged between Northern ships and land forces. Several reports indicate that a flagman conveyed Farragut's legendary command, "Damn the torpedoes, full speed ahead!"
While a number of banner exchanges succeeded, others were intercepted by experienced observers on both sides. Always security conscious, Albert Myer applied for a patent for a CIPHER DISK intended to accompany the wig-wag system. The disk used only the numerals 1 and 8 in various combinations on its outer ring and a randomly placed alphabet on its movable inner ring. Myer specified that those exchanging messages each have one of his disks and a prearranged plan to coordinate it with the flags or other visual signals. His goal was to give better protection to the observable aspects of a system like wigwag by sending signals with numbers that could only be decrypted with the disks.
With a planned starting point such as A = 118, the transmitter would send the numbers 8881, 888, 11, 18, and 888. The recipient would have his disk set at A = 118, and a brief check of the other alignments would reveal the letters of the word union.
In 1863, Myer's disk did improve the security of wig-wag. However, wire telegraphy had obvious advantages, and that became the predominant system for long distance communication. Myer, meanwhile, developed yet another signaling system, using rockets and Roman candles to signal alerts and to provide artificial illumination during night assaults (see VERY LIGHT). His inventiveness, foresight, and loyalty were rewarded when he was twice named chief signal officer of the U. S . Army.
Excerpted from: Codes and Ciphers, pp. 32-33.
Civil War (United States, 1861-1865), a war in which concealment systems played an important role, although they did not affect the outcome.
Union Gen. George McClellan, for example, used a type of word TRANSPOSITION in 1861 during his victorious campaign along the Ohio River Valley and in western Virginia. The CIPHER was created by Anson Stager, first superintendent of Western Union. Mr. Stager's cipher grew in importance as Union commander John C. Freemont and detective Allan Pinkerton applied it in the West and East, respectively. In 1862, the Stager transposition came into use throughout the Union Army, thanks to the first large-scale wartime use of the telegraph. In fact, President Lincoln frequently visited the telegraph room in the War Department to keep informed of unfolding events.
The Stager cipher was readily adaptable to telegraphy because of its easy arrangement. The message was written in lines and transcribed using the columns that the lines formed. Secrecy was provided by the order in which the columns were read, namely down one column and up another. As time passed, further security was added by NULLS, CODENAMES for special terms, and multiple directions that formed a larger maze of ROUTES necessary to trace the message.
The various branches of the Union Army did not all use the Stager cipher. Some forces, for example, continued to use elementary word transpositions and members of the new Signal Corps, such as Sgt. Edwin Hawley and Maj. ALBERT MYER, devised other methods. Hawley's polyalphabetic creation (see POLYALPHABETIC SUBSTITUTION), was a set of 26 wooden pieces bearing different ClPHERTEXT alphabets used with a KEYWORD, became the first American cipher method to be patented. Myer, the Signal Corps' commander, also developed a ClPHER DISK as well as a signaling system for flags, torches, and other hand-held objects.
Both sides were often able to intercept such visual signals, though a number of them were purposely falsified. But the South's efforts in CRYPTOGRAPHY and CRYPTANALYSIS did not compare favorably with those of the North. Gen. Albert Sidney Johnston used a CAESAR SUBSTITUTION to communicate with Gen. Pierre Beauregard during the devastating Battle of Shiloh, and Johnston and Confederate President Jefferson Davis used a dictionary for a book CODE. Southern naval officers sent messages in dictionary-based codes as they planned attacks on Northern shipping.
The South's cryptographers also put their faith in BLAISE DE VIGENERE'S method, with its table of 26 alphabets, row shifts, and KEY alphabet for encipherment. Yet because of transmission errors by their own cipher clerks using MORSE CODE, the Confederate officers often had a more difficult time deciphering their own communiques than did the Union cryptanalysts (see THE SACRED THREE).