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Wigwag flags - aerial telegraphy

About Wigwag

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About Wigwag

Wigwag - or more formally, aerial telegraphy - is the system of sending messages by waving a single flag. It differs from flag semaphore in that it uses one flag rather than two, and the symbols for each letter are represented by the motion of the flag rather than its position. It was invented by US Army surgeon Major Albert J. Myer in the 1850s and officially adopted by the US Army in 1860, shortly before the beginning of the American Civil War, during which it was extensively used by both sides; this also resulted in formation of a Signal Corps in each of the belligerent armies, the Confederate Army in 1862 and the US Army in 1863, the latter continuing to present times. After the war, the wigwag was kept in use and also spread to other countries, to be used, among others, in the Boer War. It was eventually displaced by the spread of electrical telegraphy or, where that service was not available, by the flag semaphore for short distances and the heliograph for long distances, coming out of use in the early 20th century. The current US Army Signal Corps branch insignia, introduced in 1884, consists of two wigwag flags crossed and a flaming torch.

images by António Martins-Tuválkin, 12 May 2024 and Tomislav Todorovic, 24 June 2025

The wigwag flags are larger than those for the semaphore, as well as hoisted on longer staffs (held by both hands), thus allowing for the message transmission over greater distances. Three flag designs exist:
- white flag with red square, used against dark backgrounds;
- red flag with white square, used against light or varied backgrounds and also at sea;
- black flag with white square, used against a background of snow.

The standard flag sizes were:
- 4 ft (120 cm), basic size (all three designs),
- 6 ft (180 cm), used for greater range (white and black flags), and
- 2 ft (60 cm), used for less conspicuous messaging (white and red flags).

By day, the flags could be replaced by the disks, made of canvas on metal or wood frames, 12 to 18 in (30 to 46 cm) in diameter. By night, the torches (kerosene lanterns) were used, one attached to the staff and the other 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. The signals were read via the telescope.

The original code created by Myer was based on three motions, each starting from and ending in an upright position;
- motion 1, with lowering the flag to the bearer's right side,
- motion 2, with lowering the flag to the bearer's left side, and
- motion 3, with lowering the flag to the bearer's front.
The letters were coded as the combinations of motions 1 and 2, the motion 3 appearing only in the control characters. The numerals were coded separately, but these codes were also used as the control signals; alternatively, the Roman numerals could be used.

To start the communication, the sender sends the "attention" signal (continuous waving from side to side) until the receiver replies with the "understood" signal (22.22.22.3), to which the sender replies with "understood" and proceeds to send the message. The elements of a character are performed rapidly without pause between them, only returning the flag to the rest position at the end of the character. The message is formatted by the signals "end of word" (3), "end of sentence" (33) and "end of message" (333).

Myer's code remained in use in the US until 1886 when it was replaced by Morse code, to be revived in 1896 and officially discontinued in 1912 when International Morse code was mandated for all types of visual signaling. In wigwag, the Morse code was applied by representing dots and dashes with the motions 1 and 2, respectively.

Sources:
[1] Wigwag at Wikipedia: https://en.wikipedia.org/wiki/Wigwag_(flag_signals)

[2] Morse code at Wikipedia - Use in wigwag: https://en.wikipedia.org/wiki/Telegraph_code#Comparison_of_flag_codes

[3] US Army Signal Corps at Wikipedia - Branch insignia: https://en.wikipedia.org/wiki/United_States_Army_Signal_Corps#Branch_insignia

Tomislav Todorovic, 24 June 2025