Battles are won not just with soldiers and weapons but also with information. An army that responds quickly to changing conditions can defeat an opponent that has it outgunned and outmanned. Gathering information is important, but getting that information to those who can use it is equally so. In every modern army good communications are essential; otherwise, all the fancy hardware is useless. Communications is a recognized military specialty today, and that recognition began with a young U.S. Army surgeon named Albert J. Myer just before the start of the Civil War.

In 1851, while a medical student, Myer developed a visual telegraph system to enable the deaf to communicate. It used fingers to transmit a binary code, moving them to the left for a 1 and to the right for a 2. Three years later Myer joined the Army as a surgeon, and while posted in Texas he began to consider the possibilities of military signaling. He saw how Indians used visual signals to send messages and realized that in the clear air of the Great Plains his telegraph system could be adapted to communicate instantaneously over miles. In 1856 Myer wrote Secretary of War Jefferson Davis to suggest its adoption by the Army.

Davis wasn’t interested, but his successor, John B. Floyd, was. In 1858 the Army agreed to test the system, and during the fall of 1859 Myer worked on developing it, with the assistance of a young instructor from West Point named Edward Porter Alexander. They quickly decided to use flags for daytime signaling and torches at night, and over the next several months they experimented with various sizes and colors of flags, lengths and materials for the poles, construction and fuel for the torches, and so on. Eventually they settled on a large square flag, white with a red square in the middle or vice versa, depending on the background to be signaled against. The completed system was portable—it could go anywhere a soldier could go, on foot or on horseback—and much less cumbersome than the field telegraph then coming into use. Wigwag—as the system became known, from the back-and-forth motion of the flags—was superior to flag semaphore, which was not in use in the Army at that time, because as long as you could make out the motion of the flag or torch, you didn’t need to see the position of the signaler’s arms.

In early 1860 Myer and Alexander appeared before the Senate Military Affairs Committee to support the establishment of a signal officer on the Army staff. Jefferson Davis, now chairman of that committee, opposed the bill, but it passed and was signed by President Buchanan on June 21, 1860. Six days later Myer became the Army’s first signal officer, and almost immediately he was sent to the New Mexico Territory to join the campaign against the Navajos. Upon his arrival he recruited a signal party, and it was so successful that the commander reported that he was able to discharge all his scouts and spies.

In the U.S. Army’s first major battle after adopting wigwag, however, the system worked to its disadvantage. Alexander was a Georgian, and when his state seceded, he sided with the South. Davis overcame his reluctance to establish a new branch of the service and appointed Alexander the first Confederate signal officer. At Bull Run, on July 21, 1861, he had a trained party ready for the Union advance. From his vantage point (now known as Signal Hill) behind the Confederate position, Alexander saw Irvin McDowell’s Federal troops trying to outflank Nathan Evans’s brigade, at the extreme left of the Rebel line. From eight miles away he wigwagged the message LOOK OUT FOR YOUR LEFT YOU ARE FLANKED . EvanS Quickly moved some of his men to meet the attack, and the Union thrust was slowed so that Confederate reinforcements could be brought to bear.

Alexander’s success helped establish wigwag, and the specialty of communications, in both armies. He soon switched to artillery, but by then Confederate and Union Signal Corps soldiers were being used in all theaters. Myer served as signal officer with the Army of the Potomac in the Peninsula campaign and at Antietam; he was then recalled to Washington and eventually promoted from major to colonel. By the end of the war the system had even spread to the sea.

Wigwag has long since been superseded by electronics for most military uses. But the red-and-white flags and torch live on in the insignia of today’s Army Signal Corps. They serve as a reminder of the days when an Army doctor and his former assistant demonstrated the importance of information in modern warfare.