The Signal Corps: War Communication Before Technology

Today our military has access to many ways to observe the enemy. From unmanned drones that fly reconnaissance missions to satellite imagery and infrared sensors to detect enemy presence, modern technology permits battles to be plotted by GPS and tracked via computer in ways that earlier military units could not even imagine.

On a recent visit to Gettysburg Battlefield, the licensed battlefield guide reminded our group of the Civil War novel, Killer Angels by Michael Shaara. My interest was caught immediately by the opening chapter, “The Spy,” which focuses on a lone rider, a former actor and non-military man, who scouted the movement of Union troops for Lieutenant General James Longstreet, Robert E. Lee’s second in command.

The thought of this “hired gun” being an important part of the Confederate war cabinet sent me on a mission to find out more about how the military observed the enemy and communicated their movements during the Civil War.

As indicated in Killer Angels, spies (called scouts if they were in military uniform) were important for providing intelligence to the officers. The spies or scouts rode through potential battlefield areas, observing troop movement and talking to townspeople to pick up any information the locals had gleaned as to the plans of the enemy.

Letters with military orders were sent by courier, from brigade to nearby brigade as well as for much longer distances. These missives were often sent in an agreed-upon code.

The telegraph was introduced into this country in 1835-36, and by 1861, a private telegraph company, Western Union, had wired the U.S. from coast to coast. The system, using wires that could carry Morse code signals, was so popular that when possible, the military would arrive in an area and string wires to provide a way to communicate to the nearest headquarters.

The military was also beginning to look to the air. A self-made aeronautics expert, Thaddeus Lowe, had been experimenting with ballooning before the war, and in July of 1861, Abraham Lincoln appointed him Chief Aeronaut of the Union Army Balloon Corps. These hot air balloons were primarily used for general surveillance of an area. Balloons were also used occasionally during battles, however, they were difficult to transport so they often couldn’t reach the location in time.

In a unique combination of two innovative services, Thaddeus Lowe convinced Union Major General George B. McClellan to permit him to attempt to relay information via telegraph, but from a balloon. In 1862 the Army of the Potomac, led by McClellan, pushed south to the outskirts of Richmond. Working behind Union lines, Lowe guided a tethered balloon up about 2,000 feet in the air where he observed the actions and movement of the Confederates from the vantage point of the balloon. The balloon carried a telegraph with wires that were strung to the ground, so the telegraph operator traveling with Lowe relayed in signals everything Lowe saw.

The Signal Corps

But perhaps one of the most important communication tools of the Civil War was a system of flag signals that were used by both Union and Confederate troops. An assistant surgeon in the pre-Civil War army, Albert James Myer, was the fellow who developed the idea. Myer was on the side of the Union but ironically, his idea was first used by Confederate soldiers when one of his apprentices, who was from the South, went home and shared the system with the southern army at the start of the war.

The concept of a flag being used to signal troop movement sounds simple enough, but the method Myer developed was actually quite complex. There were three basic signals used. A wave to the left signaled “one,” a wave to the right signaled “two,” and a wave forward signaled a break between words or messages. Certain flag waves were determined for each letter of the alphabet so that words could be spelled out. For example:
A is one, two, or 1, 2.
B is one, two, two, one, or 1221.
C is two, one, two 212, and so forth.

The messages were not simple; they ranged from “Look to the left and shoot into the bushes” to complex multi-word messages concerning future strategy. Multiple messages were also sent at the same time. A gun fired once indicated a first message; two shots indicated the start of a second message, etc. Very important messages were to be verified by the receiving station repeating them.

Since both sides based their system on Myer’s idea, they realized that if the enemy could see the signals, they could probably interpret the conversation. One of the tools signal corps members carried was a two-disk device that permitted them to “dial” a different code. By signaling to the recipient what cipher they were using, they could then send encrypted messages.

However, the signal corps faced some interesting challenges, beginning with attracting the attention of someone to whom they wanted to signal. A government instruction booklet from 1864 explains that attempts to attract attention “should never be abandoned, until every device has been exhausted; and they should be renewed and continued at different hours of the day and night…” Signaling for attention ranged from running back and forth to flag waving. [“A Manual of Signals: For the Use of Signal Officers in the Field,” 1864.]

Signal Corps members carried with them a staff and two flags. During the day the flag color that was most visible was a white flag with a red square but if there was snow on the ground, the flag used was black. They also carried a torch to use for nighttime signaling. When using a torch, the operator placed a second torch at his feet as a reference point to clarify the signals. To better receive messages, members of the signal corps all carried high-powered telescopes.

These men often worked in isolated observation towers built for them by the military. By putting the signal corpsmen up high, they were more visible, and in areas with a lot of fighting, the towers were spaced so that each tower could be seen by the next one so that messages could travel from tower to tower by relay. If there was no time for building a tower, they would clamber up rocks or climb a tree, or sometimes move out in front of the troops so more people could see them. Mortality was high.

While today’s battles are just as frightening for the soldiers as were the battles fought between the armies of the Blue and the Gray, today’s soldiers can be grateful for the improved technology that drastically improves their odds.

If you enjoyed this post, sign up for my blog alerts (button above). This spring I’ll be writing more about this era when I visit some of the locations that are part of the Journey through Hallowed Ground.

My last e-newsletter concerned communication in the days before e-mail. If you’d like a copy of my e-newsletter with great stories about the postal service, send an e-mail with “U.S. mail” in the subject line: [email protected].

Share with Others!

4 thoughts on “The Signal Corps: War Communication Before Technology”

  1. My brother suggested I might like this website. He used to be totally right.
    This put up actually made my day. You cann’t consider
    just how so much time I had spent for this info! Thank

  2. Pingback: Bugle Calls and the Origin of TAPS - America Comes Alive

Leave a Comment

Your email address will not be published. Required fields are marked *

Translate »
Scroll to Top