From the Revolutionary War to the present, the American military has used communications in order to command and control its forces and other assets, but the technology has changed dramatically. Methods employed during the nation's war for independence (messengers, signal lights, and voice commands) differed little from those used by ancient armies.

During the Civil War, visual signaling remained the primary communications method. The utility of the electric telegraph (invented 1837) had been amply demonstrated by European armies since the 1850s; but Albert J. Myer gave it little attention when designing the nation's first military communications organization, the U.S. Army Signal Corps. Established by an act of Congress on 21 June 1860, the Signal Corps employed Myer's “wigwag” system. Using an adaptation of the Bain telegraph code, movements of flags (and at night, torches) transmitted tactical communications within visual range. Although army signalers operated “telegraph trains” (communications wagons with telegraphs and field wire), fixed wire communications were beyond Myer's purview. With regular trips to the War Department, President Lincoln read the latest telegraphic reports on the progress of the war. The conduit for that information, more than likely, was the rival U.S. Military Telegraph, a contract firm that used commercial lines and civilian employees to meet the administrative and strategic needs of the army.

After the war, the Signal Corps assumed responsibility for the electric telegraph and used it to create a national weather service as well as a military communications network. Although visual signaling—wigwag, sun‐powered heliograph, and observation balloons—remained important to the U.S. military, the Spanish‐American War found commercial and military telegraph enjoying extensive use. Commanders in widely dispersed theaters of war—Cuba, Puerto Rico, and the Philippines—made use of both military and commercial telegraph. Telegraph and ocean cable connected the front lines of Cuba with defense planners in Washington. Wire communications facilities across the Philippine Islands linked the archipelago by submarine cable. At the same time, Adolphus W. Greely (chief signal officer 1887–1906) adapted and equipped the army with emerging late nineteenth‐century technology, such as the telephone (invented 1876), to command and control its forces. Its use was demonstrated by the telephone system in Cuba that enabled Gen. William Shafter's Fifth Army to communicate within yards of the front line, as well as with the admiral of the U.S. Fleet.

While providing a communications network and trying to quell the Philippine War (1899–1902), the Signal Corps simultaneously supported the army on another frontier. Signal Corps celebrities such as then Lt. Billy Mitchell helped to construct the Washington‐Alaska Military Cable and Telegraph System (WAMCATS). The network, which connected the region's isolated military posts, helped the army coordinate its peacekeeping efforts in the territory during the Alaska gold rush. Renamed the Alaska Communication System in 1936, it remained under military control for over sixty years. Radio replaced Alaska's telegraph system in 1928, owing much to the efforts of George Owen Squier (chief signal officer 1917–24), who tested Marconi's invention, the wireless (1895), for military use.

The U.S. Army and the U.S. Navy both employed the wireless. In 1904, a radio station in the Boston Navy Yard transmitted the first official Naval Observatory time. Although experimentation continued and the navy employed wireless to transmit time and weather reports, the navy's admirals had little faith in its tactical uses.

The Army Signal Corps introduced the first portable wireless sets into the field in 1906, and began experimenting with radio telephony (voice radio) the following year. In 1914, it tested a radio set mounted in an automobile. Parallel efforts by the navy during this period included in‐house experimentation and support of the commercial development of radio. Regarded as a novelty, however, radio remained largely unused. Army land forces in World War I relied on the telephone, telegraph, and even homing pigeons for communications in the era of trench warfare.

Supporting the American Expeditionary Forces, the army was also responsible for combat photography and aviation. Nevertheless, the Signal Corps' grandest achievement was the establishment of a massive wire communications system that ran from the seacoast to the American battle zone in France. The system consisted of literally thousands of miles of administrative and combat lines: 134 permanent telegraph offices and 273 telephone exchanges, facilitated by 200 bilingual American telephone operators. Multiplex printing telegraph equipment linked Tours, Chaumont, Paris, and London.

The army's communications arm also oversaw the adaptation of the airplane to military use. With its genesis in Civil War and Spanish‐American War observation balloons, the Signal Corps purchased a Wright brothers' flying machine in 1908. James Allen (chief signal officer 1906–13) and his immediate successors perceived the airplane as an observation platform and vehicle for courier service. When aviation's role as a fighting and bombing force expanded during World War I, the army created the Army Air Service (1918), separating aviation from the Signal Corps.

Experimentation before and during World War I contributed to the Signal Corps' development of radio for military purposes. Stepping stones included the achievements of Signal Corps captain (later major) Edwin H. Armstrong. Armstrong invented a major component of amplitude modulated (AM) radio—the superhetrodyne circuit—during World War I. His next invention, frequency modulated (FM) radio, came during the interwar years. Chief Signal Officer Squier facilitated the standardization and mass production of vacuum tubes. He established the first Signal Corps Laboratory at Camp Alfred Vail, New Jersey. Introduction of the SCR‐68, an airborne radio telephone, and its companion ground set, the SCR‐67, were significant steps in the development of radio communications.

During the interwar years, developments in both wire and radio technology set the stage for communications support for World War II. Naval research included experimentation with the radio compass, airborne radio, and radio remote control. The teletype, remarkable for its accuracy, speed, and simplicity of operation, came into the arsenal in the 1930s. The battery‐powered field telephone was developed as the Germans improved both the switchboard and communications cable. The War Department Radio Net (established 1922) became the genesis for an elaborate command and control communications system that enveloped both army forces and navy ships during World War II. About the same time, the International Radio Convention (1927) adopted the navy's plan for worldwide frequency allocation.

A 25‐pound army walkie‐talkie, developed in 1934, made its debut in the army maneuvers of 1939. A truck‐mounted long‐range radio, with a 100‐mile voice range and several times greater range for Morse Code, was introduced in the 1940 Louisiana maneuvers. Captain Armstrong helped Col. Roger Colton develop his invention into the army's first FM pushbutton, crystal‐controlled, tactical radio in the Signal Corps Laboratory at Fort Monmouth, New Jersey. Although the army's armor and artillery branches communicated via FM radio (proven feasible by 1936), the infantry (as well as the navy) failed to integrate the new technology until after World War II.

Numerous countries claimed ownership of radar, developed during the 1930s. Its significance in World War II communications cannot be overstated. By 1943, the Germans were effectively using radar as an early warning and weapons‐directional device. In the United States, navy research and development paralleled that of the Army Signal Corps. Prewar, the navy installed it on ships (1940), while the army used it as a short‐range radio locator for directing searchlights. A new, long‐range aircraft detector radar, on Oahu, Hawaii, issued a warning (unfortunately ignored) when Japanese aircraft approached the island on 7 December 1941. By early 1942, the Signal Corps SCR‐517 microwave radar was used in aircraft to search for ships in the Atlantic. In 1944, a microwave SCR‐584 helped aim U.S. weapons in combat at Anzio, Italy. By the end of the war, such communications advances as the bi‐service advancement of radar, navy perfection of sonar, army development of FM radio, and overall miniaturization of electronic components laid the groundwork for the electronics and space ages to follow.

The Signal Corps used a modified SCR‐271 long‐range radar set (1946) to bounce radar signals off the Moon to test the properties of radio communications in space. Postwar navy technological achievements included over‐horizon VHF radio communications, the use of radar waves to reflect signals off the Moon (1951), and Moon‐relayed messages between Honolulu, Hawaii, and Washington (1956). Both services contributed to the development of artificial space satellites and communications. By the 1960s, rockets of the U.S. Air Force were sending manned and unmanned vehicles into space.

Improved radar supported land and air forces and naval batteries in the conduct of the Korean War. The Signal Corps played a major supporting role in that conflict. Although doctrine dictated wire as the primary means of communication, the exigencies of Korea—distance, terrain, primitive roads—led to a dependence on very high frequency (VHF) radio. VHF, effective far beyond its 25‐mile range, carried teletype as well as voice traffic. It proved adaptable to the frequent infantry moves characteristic of the fighting in the first two years of the conflict. But line‐of‐sight properties restricted its usage; VHF station components, weighing hundreds of pounds, often required transportation to—and operation and maintenance from—high, remote communication sites. In spite of the difficulties, army communicators proclaimed VHF the backbone of communications during the Korean War.

Between Korea and Vietnam, military efforts again focused on the peaceful uses of communications. The army, in 1958, used its technology to explore outer space. The Signal Corps' Space Sentry bounced signals from the Moon, developing the ability to ensure the close tracking of satellites. The same year, Vanguard II's infrared scanning devices mapped the cloud cover over the Earth.

Technological advances in communications during the Vietnam War were the end product of twenty years of research and experimentation by the army, navy, and air force. Miniaturized electronic components increased the payloads of U.S. communications satellites propelled into space by air force boosters. One notable benefit was initiation of the first operational satellite communications system in history when the Army Satellite Communications Command established two clear channels from Tan Son Nhut, South Vietnam, to Hawaii (1964).

Radio transmission had improved as well. Line‐of‐sight wave transmission was surpassed by tropospheric scatter or troposcatter propagation radio with a maximum 400‐mile range. The new technology enabled radio waves to travel long distances by using special antennas to bounce them off clouds of ionized particles in the higher ionosphere before they returned to Earth hundreds of miles away.

Military communications support in Southeast Asia proved that advanced electronics could master the geography. Although Vietnam's Integrated Wideband Communications System (established and funded by the air force and operated jointly with the army) never fulfilled the promise of a regional civil‐military network, it demonstrated the need and effectiveness of a high‐capacity area telecommunications system in an undeveloped region. More important, the wideband system reflected a permanent move to an area‐oriented communications doctrine. Improved technology was directly responsible for the shift in focus.

As a joint‐services endeavor, Vietnam communications included numerous examples of inter‐service cooperation. For example, army field commanders enjoyed rapid aircraft response because of connectivity with air force support centers. Joint army‐navy mobile riverine forces, using command and communications boats, had well established internal as well as external communications with the South Vietnamese army. A continuing problem in Vietnam, security was addressed first by the navy's “Talk Quick” system which preceded the army's automatic secure voice system (1967).

Major communications systems in Vietnam included the 1st Signal Brigade's Southeast Asia Defense Communications System and the Southeast Asia Automatic Telephone Service (1968). The latter comprised 9 switches connected to 54 automatic army, navy, and air force dial exchanges. Overall, communications support for the Vietnam war could be characterized as the beginning of an ongoing trend toward the use of commercial‐type facilities for both strategic and tactical communications. While mobile multichannel radios, switchboards, and teletype centers linked headquarters throughout the chain of command, strategic and administrative networks comprised a variety of commercial sets.

Changes in military strategy and tactics such as the long‐range and heavy logistical requirements of modern weapons, and reliance on coordinated air‐ground operations, both prevalent in Vietnam, dictated more flexible and extensive communications support than that offered by traditional chains of command. Technical advances in communications made it possible—indeed, imperative—to create interconnecting area networks. The merger of tactical and strategic communications became official in 1966 with the formation of the 1st Signal Brigade. As part of the Strategic Communications Command, area networks linked fighters with intelligence, personnel, and logistical centers in the United States. At the same time, combat commanders kept organic tactical communications to respond to military requirements.

Higher‐echelon advances did little to change Vietnam's combat communications from those of previous conflicts. Field telephones connected by single‐strand wire linked artillery battery, guns, fire direction centers, and commanders. Infantry platoon command posts used small field switchboards and wire lines to connect squads, sentries, and listening posts. The 173rd Airborne Brigade, in 1965, deemed the PRC‐25 (transistorized FM voice radio) its greatest communications device. Hand‐held, vehicle‐, and aircraft‐mounted PRC‐25s were the primary means of combat communication for army units from squads through division level.

The Vietnam conflict demonstrated the interdependence of the army, navy, and air forces in the conduct of mid‐twentieth‐century warfare. The secretary of defense acknowledged this fact in such cooperative efforts as the Joint Tactical Satellite Research and Development Program (1965). At the same time, the communications arms of the various military branches continued to invest in their own unique information systems.

Post‐Vietnam technology further changed the face of military communications. The 1970s development of the semiconductor dramatically decreased size and power requirements of communications systems. The microprocessor revolution, in turn, led to the development of modules rather than discrete systems. Miniaturization, greater standardization, and modules all made commercial equipment cheaper, more adaptable, mobile, and secure.

The U.S. military's post–Cold War operations revealed major weaknesses in the Department of Defense's (DoD) efforts to weld its various communications assets into a cohesive whole. Communicators in Operation Urgent Fury (Grenada, 1983) encountered major obstacles in the coordination and provision of support for the Joint Task Force. Both the DoD and Congress took positive steps to strengthen cooperation among the various service components—DoD through the establishment of the Joint Tactical Command Control and Communications Agency (1984) and Congress with the Goldwater‐Nichols Act (1986). The positive results of these and other actions became clear in Operation Just Cause (Panama, 1989–90).

Operation Desert Storm (1990–91), a major joint operation directed by the U.S. Central Command, provided a true test of service cooperation. The Persian Gulf War demonstrated that military communications had expanded and transformed into information technology. In the few years between Panama and the gulf, joint training had become the rule.

As information systems achieved equal footing with military hardware in the conduct of the Gulf War, all of the services incorporated numerous commercially produced systems. The Army Signal Corps' network, connected with those of the other services and Allied Coalition forces, spanned the geographic area with commercially developed cellular telephone and a single‐channel ground and airborne radio system.

Operation Desert Storm left little doubt that late twentieth‐century military communications embraced all aspects of information management. Using multimedia sources, communicators need to get the right information to the right people almost instantaneously. At the end of the twentieth century, information activities in war have equaled and in some cases supplanted industrial activities.

Military communication—or more accurately, information management—presents a seamless network on the late twentieth‐century battlefield. As a result of technological advancements, the centerpiece of the battlefield is no longer simply the weapons platforms but also an information grid into which weapons are plugged.

Information technology will continue to transform military communications. Because the value of information increases exponentially through dissemination, its potential is virtually limitless.

[See also Combat Support; Command and Control; Satellites, Reconnaissance.]

Bibliography

• U.S. Naval Communications Chronological History, 1961.
• Carroll V. Glines, Jr. Compact History of the United States Air Force, 1973.
• Paul J. Scheips, Military Signal Communications, 2 vols., 1980.
• John D. Bergen, A Test For Technology, 1986.
• John G. Westover, Combat Support in Korea, 1987.
• Kathy R. Coker and Carol E. Stokes, A Concise History of the U.S. Army Signal Corps, 1995.
• Rebecca Robbins Raines, Getting the Message Through, 1996