The U.S. Army's Signal Corps has now been around for 150 years at the forefront of technologies from the telegraph to radio, radar, and satellite communications.
In 1860, the man in the center of this photo, Albert Myer, became the first-ever signal officer of the U.S. Army. (He's seen here some months later during the Peninsula campaign of the Civil War.) While the government liked Myer's ideas on signaling well enough to establish the U.S. Army Signal Corps at that time, the early years of the undertaking faced any number of challenges--ungainly technology, bureaucratic infighting, lack of funding and staffing. But the seed was planted in those early days, and the Signal Corps has now been around for 150 years (making this year the sesquicentennial), at the forefront of technologies from the telegraph to radio, radar, and satellite communications.
The immediate impetus for the Signal Corps was a decidedly low-tech flag system devised by Myer while he was serving as an Army surgeon and based on his medical dissertation, "A New Sign Language for Deaf Mutes." (Myer also had experience as a telegraph operator.) Known officially as the General Service Code, Myer's military signaling system is more familiarly referred to as "wigwag."
Wigwag was a simple, almost binary, code: wave the signal flag to the left to represent "one" or wave it to the right to represent "two." Letters of the alphabet were then constructed from combinations of one and two. For instance, A was 22, B was 2112, and C was 121.
Wigwag depended on line of sight for the messages transmitted by flag, which led to the construction of towers such as this one from sometime in the 1860s. The flags were sizable--the square fabric would typically measure 4 feet per side, but sometimes as much as 6 feet. They were waved at the end of a 12-foot hickory staff, which surely made for quite a workout. (Torches were sometimes used instead; they were more diminutive 18-inch copper cylinders.)
The electric telegraph had come on the scene in the 1840s and was gradually being adopted for both civilian and military uses. In the U.S. Army during the Civil War, however, the electric telegraph was by and large kept out of the hands of military commanders in the field and served instead as a rather private tool for Secretary of War Edwin Stanton and his personal staff--much to the consternation of Chief Signal Officer Myer.
The Signal Corps made do with the less powerful Beardslee telegraph, a magneto-electrical device (pictured here). Writes Raines, describing the battle of Chancellorsville: "The Beardslee's revolving magnets could not generate enough electricity to transmit signals more than about five to eight miles. Therefore, it alone could not connect the new commander of the Army of the Potomac, Maj. Gen. Joseph Hooker, situated on the south side of the Rappahannock, with his chief of staff, General Butterfield, at general headquarters over ten miles away on the other side of the river. Using both electrical and visual signals, the Signal Corps took three hours to deliver messages between them...
"The system broke down completely when Hooker and Butterfield overloaded it, sending more messages than the officers and equipment could handle...[T]he inadequacy of the Union's field communications contributed to the failure of the Chancellorsville campaign."
This map shows the extent of the U.S. Signal Corps' telegraph lines as of 1885. And that rather limited deployment even includes some lines marked as abandoned, such as the stretch between San Diego, Calif., and Yuma, Ariz.
After the Civil War, with the Army greatly reduced in size (and funding), the Signal Corps took on a new, more scientific--and less martial--responsibility. A law established in 1870 directed the War Department to set up a national weather service, whose responsibilities would include "taking meteorological observations at the military stations in the interior of the continent, and at other points in the States and Territories of the United States, and for giving notice on the northern lakes and on the seacoast, by magnetic telegraph and marine signals, of the approach and force of storms."
In 1891, the weather service was transferred to the Agriculture Department. The photo here shows a Signal Corps weather station on Pikes Peak, in Colorado, in the 1880s.
Wigwag flags go ashore in Cuba during the Spanish-American War in 1898. At the time the war started in April of that year, the Signal Corps had only eight officers, 50 enlisted men, and $800 to its name. It got an appropriation of about $600,000 to get it through the end of the year. (The Army today has about 65,000 Signal soldiers.)
The General Service Code--the ones and twos indicated by the flag-waving--actually remained in use by the U.S. Army until 1912.
Technological advances started to rev up in the late 19th and early 20th centuries. Here, in the tent, we see an early field telephone in use near San Juan Hill in Cuba in 1898.
The Army's Chief Signal Officer during that era, Adolphus Greely, gets credit for pushing the Signal Corps into the modern age. "Thanks to Greely's efforts," writes Raines, "the War with Spain became the first conflict fought by the United States in which electrical communications played a predominant role. For tactical purposes, the Signal Corps established telephone communication within camps and headquarters. For long-distance communication, it installed telegraph lines... Through the connections with the undersea cable, [Maj. Gen. William R.] Shafter could communicate with Washington within twenty minutes even in the midst of battle."
And here's what it looked like at the other end of the cable: this is the White House communications center in 1898, known at the time as the Telegraph and Cipher Center. (It is a precursor to today's White House Situation Room.) The gent at the roll-top desk at left, who was in charge of operations there, is Capt. Benjamin F. Montgomery of the U.S. Signal Corps.
As the 19th century gave way to the 20th, the Signal Corps made a quick transition through several generations of aviation technology. It took on the task, for instance, of experimenting with balloons for observation and reconnaissance, often with, first, telegraph and then telephone lines running down to the ground. During the fighting in Cuba, however, troops found that the big, anchored balloons were easy targets for the other side. There were also ongoing problems getting funding and equipment to generate the gas used to inflate the balloons.
Pictured here is the balloon house at Fort Myer, Va., in about 1910.
Like others in the early days of military aviation, the Signal Corps toyed with dirigibles (this one is at Fort Myer, in 1908). In 1907, Chief Signal Officer James Allen formally established an aeronautical division in the Corps that was to head up "all matters pertaining to military ballooning, air machines, and all kindred subjects." In December 1907, the Signal Corps took a truly historic step when it began soliciting bids for a heavier-than-air flying machine...
...which drew the attention of, among others, the Wright brothers. Five years after their unprecedented flight at Kitty Hawk, they headed to Fort Myer for trials that would show whether their new Wright Flyer had the right stuff for the U.S. Army. The specifications called for, among other things, an aircraft that could handle a sustained flight for at least an hour, hit a speed of 40 miles per hour, be easily dismantled and reassembled, and be transportable by ground on an Army wagon.
The Wright Flyer (seen here in a test flight at Fort Myer in 1908) met the grade, and in 1909 it became Signal Corps Airplane No. 1--which also made it the first official military airplane.
Writes Raines: "In the air, the Signal Corps combined its two incipient technologies by installing wireless equipment in airplanes. In 1911 a message was successfully transmitted from an Army airplane over a distance of two miles; a year later the distance had increased to fifty miles. Improvement came steadily. By 1916 a pilot at the San Diego school was sending signals and messages from an airplane over 140 miles distant, and plane-to-plane communication was achieved for the first time."
With the advent of wireless technology, the Signal Corps--like the world at large--was entering the Age of Radio. Also in the early years of the 20th century, people like George Squier, a Signal Corps officer, were working to develop "wired wireless" capabilities--that is, the transmission of radio signals via wire. That allowed for multiplexing: multiple messages traversing the same wire simultaneously, or radio, telephone, and telegraph signals sharing a wire but not interfering with each other.
Squier is see here later in his career (probably the 1920s), by now a colonel, contemplating radio equipment in the Signal Development Lab at Fort Monmouth, N.J. He was also instrumental in the development of the Signal Corps' aviation efforts.
During World War I, the U.S. military leaned heavily on the expertise and employees of the Bell System, headed by AT&T. "Ultimately," writes Raines, "the Bell System provided twelve telegraph battalions to the war effort (numbered 401 to 412) that served at the army and corps levels. Each unit comprised men drawn from a regional company. The 406th Telegraph Battalion, for example, contained employees from Pennsylvania Bell, while the 411th came from Pacific Bell."
Meanwhile, the war effort also called upon the services of large numbers of women, quaintly referred to as "Hello Girls." Some 200 of them served as telephone operators on switchboard in England and France.
Shortly after the war, the Signal Corps helped set up a nationwide radio network to handle War Department communications across the U.S. Once that was up and running, a War Department Message Center was established in 1923 to coordinate radio, telegraph, and cable dispatches. Radio signals initially were relayed cross-country through stations in places such as Fort Leavenworth, Kan. (often arriving the next day), but with the adoption of shortwave transmission technology, by 1929 Washington was able to communicate directly with San Francisco.
Pictured here are radio transmitters at the War Department Message Center in the 1930s. The man at left is RCA bigwig David Sarnoff.
In the period between World War I and World War II, radio technology was catching on in a big way, even as wired communications retained a central role, and the Signal Corps began moving in a significant way to shortwave operations. In 1929, the War Department had established direct radio communications between Washington, D.C., and San Francisco. Pictured here is a field radio in use during the 1930s, the SCR-131. It worked in the 4MHz to 4.36MHz range, powered by dry batteries and a hand generator and had an LP-7 loop antenna for transmitting and receiving.
Most of us think of the walkie-talkie as a smallish handheld device, but the original version had to be carried around in a backpack. (It weighed 35 pounds.) Designated the SCR-300, the Motorola-built, voice-only FM device worked in the 40MHz to 48MHz range and had a range of 2 to 3 miles. The first models reached soldiers in the field in 1943.
FM radios, known for the clarity of their signals, were a godsend to U.S. forces. Raines cites the praise of a radio operator serving in an infantry battalion: "FM saved lives and won battles because it speeded our communications and enabled us to move more quickly than the Germans, who had to depend on AM."
The soldier in the center is using the SCR-536 "handie-talkie" during action on Okinawa. The 5-pound device, also built by Motorola, used AM signals in the 3.5-6MHz range. It had a range of up to about 1 mile and was a staple of front-line operations.
Encryption is a key element of military communications, as is code-breaking to ferret out the actual message from encrypted signals. One edge that the U.S. military had during World War II was the ability to draw on challenging and little-known Native American languages--including Cherokee, Choctaw, Comanche, and Navajo--to encode transmissions. Pictured here are two of the Signal Corps' Navajo code-talkers in Australia in July 1943.
In the years leading up to World War II, the Signal Corps began working in earnest with a new technology: radar. Short for "radio detection and ranging," radar was a significant advance that used radio signals for more than just person-to-person communications or broadcasts of musical performances--in this case, using radio echoes to track objects such as airplanes moving through the sky, even in darkness or cloudy weather. This picture shows the early, short-range SCR-268 radar set, which worked on the 205MHz band and was designed to control searchlights and antiaircraft guns. It could detect aerial targets up to about 22 miles away.
The SCR-271, which perched on a 100-foot tower and worked on the 105MHz band, was a long-range radar used for air defense along the U.S. coastline. How long-range? With some alterations, very:
In January 1946, scientists working for the Signal Corps used a modified version of the antenna to bounce radio signals off the moon, more than 200,000 miles away from Earth. That accomplishment, which came a decade before the Soviet Union launched the first manmade satellite into orbit, demonstrated that it would be possible for people on Earth to communicate electronically with someone in space.
For all the advances in wireless technology, the Signal Corps still relied heavily on wire during the Korean War. Mountainous terrain and long distances between headquarters units presented a significant challenge for line-of-sight radio communications, while batteries for radio sets were either aging and weak, or hard to get.
"Wire communications proved equally tenuous," Raines writes. "Signalmen struggled to string wire through a tortured topography of ridges, ravines, and rice paddies. Wire teams also made attractive targets for enemy ambushes, and many signalmen became casualties from such encounters. Where telephone lines could be installed, they proved difficult to maintain. Enemy artillery and tanks broke the wires, and sabotage inflicted further damage. Even fleeing refugees sometimes cut the wire, using portions as harnesses to secure their possessions."
The Signal Corps continued to be an early adopter at the dawning of the Space Age. This monitoring station at Camp Evans in New Jersey received signals from TIROS (the Television Infrared Observation Satellite) when, in April 1960, it became the first weather satellite for the U.S. The first orbit pictures, according to the Army, were sent to Washington on a new device called the facsimile machine.
That early fax machine, cooked up by the Signal Corps Research and Development Laboratory, "transmitted a high quality picture to its destination in just four minutes," the Army says. "As a result, the first pictures from TIROS were on the President's desk shortly after they were received from the satellite, and he personally released the information to the world."
The initial TIROS (there would be a second one a half year later) sent home nearly 23,000 images of cloud formations, the first such views of Earth from space. Its equipment included two television cameras and a magnetic tape recorder, along with its power supply and transmitters. The satellite weighed 270 pounds.
For soldiers in the field, the Vietnam War saw the widespread use of the PRC-25 ("prick-25") radio, a transistorized FM device that operated on 920 channels. It had a range of 3 to 5 miles, though that could be boosted with help from above--aircraft tricked out with radios by the 1st Cavalry Division's 13th Signal Battalion could circle above ground units and retransmit the FM signals over distances as great as 60 miles. Gen. Creighton Abrams, who headed the Military Assistance Command in Vietnam from 1968 to 1972, called the PRC-25 "the single most important tactical item in Vietnam."
In the late 1980s, the Army began fielding Mobile Subscriber Equipment gear in a massive procurement effort with an overall cost of more than $4 billion. MSE radios replaced conventional multichannel radios, and other MSE technology included electronic switching nodes and facsimile terminals. It could also interoperate with tactical satellites and with gear from NATO allies, and it didn't require large antennas.
In the MSE communications architecture, according to Raines, each subscriber gets a unique--and portable--directory number, meaning calls could be switched automatically to wherever the subscriber was. That made it easier for command posts to move around without having to wait to be rewired.
MSE was a user-based system, which meant that the tactical units themselves operated it, while the Signal Corps served as a distributor for the equipment and as an adviser to those units. Gear could be housed in Humvees rather than large vans, and the system required less wire and cable than MSE's predecessors.
Humvees equipped with MSE gear saw action during operations Desert Shield and Desert Storm in the early 1990s. The network installed by the 11th Signal Brigade handled data traffic in and out of the combat zone that averaged 10 million words a day, according to the Army.
At the start of the second decade of the 21st century, the Army is working to create a single enterprise system out of its Land Warfare Network (LandWarNet), which is part of the larger Global Information Grid being established by the Department of Defense. The field operations portion of that is the Warfighter Information Network-Tactical (WIN-T) communications system, which will put an end to the Mobile Subscriber Equipment era ("antiquated MSE," according to a 2008 Army Posture Statement). Here, a soldier works with a mobile WIN-T satellite terminal in a December 2008 field test at Fort Huachuca, Ariz.
Like civilian systems including the Web and corporate intranets, the WIN-T system relies on Internet Protocol technology and draws significantly on commercial products and services, including the Iridium satellite network. It could also eventually incorporate 3G and 4G wireless technologies. The corporate team developing and fielding WIN-T includes General Dynamics and Lockheed Martin.
This photo shows soldiers checking out WIN-T gear during the 2008 field test at Fort Huachuca.
The two Humvees at the left are serving as point-of-presence vehicles for WIN-T during the 2008 exercise.
The vision, still being built out, is this: "WIN-T is an on-the-move, high-speed, high-capacity backbone communications network, linking warfighters in tactical ground units with commanders and the GIG," Lt. Gen. Jeffrey Sorenson, the Army's chief information officer, said in a June supplement to Signal magazine.