page_title: Wigwag (flag signals)
section_title: American Civil War
hierarchical_section_title: Wigwag (flag signals) / History / In service / American Civil War
context_page_description: Wigwag is an historical form of flag signaling that passes 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. The larger flag and its motion allow messages to be read over greater distances than semaphore. Messages could be sent at night using torches instead of flags.
  The most common code used with wigwag had three motions, only two of which were needed to form letters of the alphabet. These two were waving the flag, respectively, to the left and right – the wigwagging motion. A character was formed by sequentially displaying a number of motions. Like Morse code, the number of elements in each character was not fixed, the most common letters being assigned the shortest codes. A number of other codes were used at times, some of them with a fixed number of elements and up to four different motions. Morse code was used with wigwag after it became an international standard.
  The wigwag system was invented in the 1850s by US Army surgeon Albert J. Myer who became the first head of the Signal Corps.
context_section_description: Wigwag was used extensively by Civil War Signal Corps troops on both sides, and was an essential supplement to the electrical telegraph.  Its first use in battle was by Confederate Lieutenant Edward Porter Alexander (a former pupil of Myer) at the First Battle of Bull Run in 1861.  The signalmen on this occasion fulfilled an important function by reporting a Union attempt to turn the Confederate flank.  Myer had originally promoted the idea as a lightweight mobile system that could be carried by a single man – a common task for signalmen was to act as forward observers reporting artillery fall of shot.  As the war progressed, more substantial stations were constructed.  Enormous towers, some well over 100 feet, were built.  The Cobb's Hill tower shown in the image was built by the Appomattox River in June 1864.  Wherever possible, existing structures were used.  Building stations in trees was common, and church steeples were often used.  The system, at least on the Union side, took on the nature of a genuine communications network.  The Confederates, despite being first in the field with wigwag, and the Union side being slow to get going, never succeeded in building a network to the same extent.  The Confederate Signal Corps was simply not given resources on the same scale.
  The mere existence of a flag station could cause problems for the enemy.  Alexander, in his memoirs, referred to the Little Round Top station as "that wretched little signal station" because he was forced to make roundabout movements of his troops and artillery to avoid being observed (at this time, 1863, Alexander was no longer connected with the Signal Corps, but was in command of the artillery at the Battle of Gettysburg).  The Confederates had tried but failed to seize the position several times, including during Pickett's Charge in 1863.  During that action one of the Union defenders, Captain Davis E. Castle, continued to signal with a bedsheet after the flagman had retreated with the flags.  The 125 ft height of the Cobb's Hill tower gave it such a good view of Confederate movements that they assigned a gun battery specifically to destroy it.  They failed to achieve this and the tower remained in use until the fall of Petersburg to Union forces.
  Signalmen were sometimes assigned to ships to maintain communication between the navy and land forces.  On large operations they might also be used for ship-to-ship communication.  The signalman was posted high up on the masthead of the ship.  This was especially common on operations concerning the Mississippi River such as the Vicksburg campaign and the Siege of Port Hudson.
  The fact that the Confederates had personnel able to read the wigwag code was problematic for the Union side.  Security concerns led to a reluctance to send important messages by flag signals.  General Daniel Butterfield went so far as to order the Army of the Potomac not to use signals at all, much to the concern of its chief signal officer Benjamin F. Fisher.  To overcome this problem, the Signal Corps created a cipher disk to encode messages.  It is believed that the Confederates never broke this code.  The Union side was able to read Confederate flag signals without being discovered until at least 1864 when Myer's successor as head of the Signal Corps, William J. L. Nicodemus, published the fact in a pamphlet.  Nicodemus was dismissed in December 1864 for this breach of security and replaced by Fisher.
  Myer did not use the term wigwag in the manuals he produced.  He called the system aerial signals or aerial telegraphy.  The system probably came to be known as wigwag because of the apparently random motions of the flag as seen by an untrained observer.
caption: A Union cipher disk
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