Flag signals can mean any of various methods of using flags or pennants to send signals. Flags may have individual significance as signals, or two or more flags may be manipulated so that their relative positions convey symbols. Flag signals allowed communication at a distance before the invention of

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a tr ...

and are still used especially in connection with ships.

Flaghoist signalling

Flaghoist signalling is one or more flags (or pennants) simultaneously flying from a fixed

halyard In sailing, a halyard or halliard is a line (rope) that is used to hoist a ladder, sail, flag or yard. The term ''halyard'' comes from the phrase "to haul yards". Halyards, like most other parts of the running rigging, were classically made of ...

, and generally any method of signaling by such means. Each of the flags has a distinct shape and color combination. Each flag or combination of flags has a preassigned meaning or "code". The

International Code of Signals The International Code of Signals (ICS) is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp ("bl ...

defines a standard set of flags and associated alphabet suitable for international use, as well as a set of standard codes. Flaghoist is also used in

boat racing Boat racing is a sport in which boats, or other types of watercraft, race on water. Boat racing powered by oars is recorded as having occurred in ancient Egypt, and it is likely that people have engaged in races involving boats and other wat ...

, to warn of impending severe weather, and other specialized applications. Maritime flag signalling has a long history, especially prior to the advent of radio, and remains the preferred means of signaling in many situations. In

naval flag signalling Naval flag signalling covers various forms of flag signalling, such as semaphore or flaghoist, used by various navies; distinguished from maritime flag signalling by merchant or other non-naval vessels or flags used for identification. History N ...

, additional flags and an expanded list of signals are used for identification and commands, as well as the mercantile uses. Many navies have their own proprietary or secret codes, and use additional flags. A designator flag is used to indicate if a flaghoist signal is meant to be interpreted as an ICS signal or as a naval signal. The U.S. Navy uses a set of 68 flags, including flags for each letter of the alphabet and each numeral to convey messages of tactical or administrative nature.

Semaphore

Flag semaphore Flag semaphore (from the Ancient Greek () 'sign' and - (-) '-bearer') is a semaphore system conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Informa ...

signalling uses two flags, held in specific positions to signify letters. This method requires simple equipment but can be obscured by bad weather. A permanently installed chain of semaphore stations is a

semaphore line An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals. There are two main types of such systems; the semaphore telegraph which uses pivoted indicator arms and ...

and before the invention of the electric telegraph, was the fastest means of communication over moderately long distances.

Wig-wag flags

In the 1850s,

U.S. Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cl ...

Major Major ( commandant in certain jurisdictions) is a military rank of commissioned officer status, with corresponding ranks existing in many military forces throughout the world. When used unhyphenated and in conjunction with no other indicato ...

Albert J. Myer Albert James Myer (September 20, 1828 – August 24, 1880) was a surgeon and United States Army general. He is known as the father of the U.S. Army Signal Corps, as its first chief signal officer just prior to the American Civil War, the inventor ...

, 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 Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one ...

of dots and dashes. 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 troops on both sides in the

American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States. It was fought between the Union (American Civil War), Union ("the North") and t ...

. (Its first use in battle was by Confederate

Lieutenant A lieutenant ( , ; abbreviated Lt., Lt, LT, Lieut and similar) is a commissioned officer rank in the armed forces of many nations. The meaning of lieutenant differs in different militaries (see comparative military ranks), but it is often ...

Edward Porter Alexander at the

First Battle of Bull Run The First Battle of Bull Run (the name used by Union forces), also known as the Battle of First Manassas

in 1861. 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 cm) 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 (30 to 46 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 In computing and telecommunication, a control character or non-printing character (NPC) is a code point (a number) in a character set, that does not represent a written symbol. They are used as in-band signaling to cause effects other than the ...

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. 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". 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. 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.

Notes

Sources

*. *. *. *. *. *. *. *. *. {{div col end

External links

Flags of the World
Comprehensive flag information.
International Code of Signals For Visual, Sound and Radio Communications
United States Edition, 1969 (Revised 2003)

Collection of different flag systems.
Flag Signalling at Sea
Nice article by Captain Barrie Kent, Royal Navy.
Signal Corps Association 1860 ~ 1865
Flag practices Signal flags