Editing Flag signals (section)

==Wig-wag flags==
{{Main|Wigwag (flag signals)}}
[[File:Guidon.JPG|right|thumb|A typical [[Guidon (United States)|US Signal Corps guidon]] features wig-wag flags]]

In the 1850s, [[U.S. Army]] [[Major (rank)|Major]] [[Albert J. Myer]], a surgeon by training, developed a system using left or right movements of a flag (or torch or lantern at night). Myer's system used a single flag, waved back and forth in a binary code conceptually similar to the [[Morse code]] of dots and dashes.<ref>{{Harvnb|Raines|1996|p=5}}</ref> This is sometimes called the ''wig-wag'' method of signaling, or "wig-wagging". More mobile than previous means of optical telegraphy, as it only required one flag, this code was used extensively by [[Signal Corps in the American Civil War|Signal Corps]] troops on both sides in the [[American Civil War]].<ref>{{Harvnb|Raines|1996|pp=23–29}}</ref> (Its first use in battle was by [[Confederate States Army|Confederate]] [[Lieutenant]] [[Edward Porter Alexander]] at the [[First Battle of Bull Run]] in 1861.<ref>{{Harvnb|Alexander|1907|pp=3, 4, 14–16, 30–31}}</ref>) In this code, alphabet letters were equated with three positions of a single flag, disk, or light. The flags measured two, four, or six feet (60, 120 or 180&nbsp;cm) square and were generally either red or black banners with white square centers or white banners with red square centers.<ref name=Myer1866>{{Harvnb|Myer|1866|p=176}}</ref> The disks were 12 to 18&nbsp;inches (30 to 46&nbsp;cm) 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. The lights were kerosene lanterns 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 lantern's movements.

Myer's code was ternary (three symbols). However, only two of these symbols were used for letters, making it largely binary.  The third symbol only appeared in [[control character]]s.  Each character consisted of a combination of three basic motions (elements). The neutral position was 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. The second motion brought the device down on the left side and then returned it to the starting position. The third motion lowered the device in front of the signalman, then restored it to its vertical position.<ref>{{Harvnb|Myer|1866|p=83}}</ref>  Like Morse code, but unlike Myer's original code, this binary code did not have a fixed length for each character.  For instance, ''i'' was coded as "2", but ''d'' was coded as "222".<ref>{{Harvnb|Wolters|2013|p=10}}</ref>  Myer's 1866 manual also includes a 3-element fixed length code using four elements, and the 1872 manual has a 3-element fixed length code using three elements.<ref>{{Harvnb|Myer|1866|p=97}}</ref><ref>{{Harvnb|Myer|1872|p=96}}</ref>  There is little sign that these codes were widely used.  The 1872 manual includes a variable length code using four elements which Myer says was used by the Army, but is superseded.<ref>{{Harvnb|Myer|1872|p=107}}</ref>