The United States Army Signal Corps (USASC) is a branch of the United States Army responsible for establishing and managing the communication and information systems for the command and control of the combined arms forces. The USASC manages new technologies and capability portfolios, which are in turn transferred to other U.S. government entities. The branch's responsibilities include military intelligence, meteorological forecasting, and aviation.
The USASC supports command and control across combined arms forces. Its network operations include information assurance, information dissemination management, network management information, and management of the electromagnetic spectrum. This includes designing and installing data communications networks using single- and multichannel satellite, tropospheric scatter, terrestrial microwave switching, messaging, video teleconferencing, and visual information systems. The USASC integrates base communications and information processing management systems into a global information network intended to provide army, coalition, and joint operations with what the military calls, "knowledge dominance."
While serving as a medical officer in Texas in 1856, Chief Signal Officer Albert James Myer proposed that the Army use wigwag (or aerial telegraphy), a visual communications system that he developed for signaling. When the Army adopted his system on 21 June 1860, the USASC was created with Myer as the first and only Chief Signal Officer.
Myer's first assignment in his new position was in the early 1860s as part of the Navajo expedition in New Mexico. In June 1861, Myer's system was used to direct the fire of a harbor battery at Fort Wool against the Confederate positions opposite Fort Monroe during the Civil War. Flags were used for daytime signaling, while torches were used at night.
Until 1863, Myer relied mostly on detailed personnel. Then, on 3 March 1863, the USASC was authorized as a separate branch of the Army by an Act of Congress (Public Law No. 58 Article VIII, Section 17 and 18).
Myer's Civil War innovations included an unsuccessful balloon experiment at First Bull Run and, in response to McClellan's desire for a Signal Corps field telegraph train, an electric telegraph in the form of the Beardslee telegraph machine. During the Civil War, Wigwag began to be replaced with electric telegraph, bypassing line-of-sight restrictions.
Myer used his office in downtown Washington, D.C. to temporarily house the Signal Corps School. The location was later moved to Fort Greble, one of the Defenses of Washington during the Civil War, and then again moved to Fort Whipple, where the school remained for over 20 years and was ultimately renamed Fort Myer.
Signal Corps detachments participated in campaigns fighting Native Americans in the west, such as the Powder River Expedition of 1865.
In July 1866, Congress decided that there should be at minimum a cadre of Signal Officers, even in peacetime. It then provided one Chief Signal Officer of the Army, with the rank of Colonel. Six additional officers and 100 men were chosen from the Corps of Engineers for the Signal Corps.
The electric telegraph, in addition to visual signaling, became a USASC responsibility in 1867. Within 12 years, the Signal Corps had constructed, maintained and operated 4,000 miles of telegraph lines along the nation's western frontier.
In 1870, the Signal Corps established the Congressionally-mandated national weather service. Within a decade, with the assistance of Lieutenant Adolphus Greely, Myer commanded the weather service until his death in 1880. The Weather Bureau became part of the U.S. Department of Agriculture in 1891 and the corps retained responsibility for military meteorology.
In 1881, the Signal Corps participated in the First International Polar Year. One of the groups commanded by Lieutenant Greely became separated from their base camp and were marooned on an ice floe. Due to starvation and drowning, only seven of the original 25 volunteers survived, which meant a 28% chance of surviving.
The Signal Corps aided in the Spanish–American War of 1898 and the subsequent Philippine Insurrection. In addition to visual signaling, including heliography, the corps supplied telephone and telegraph wire lines, cable communications, enabled the use of telephones in combat, conducted combat photography, and renewed the use of balloons. Shortly after the war, the Signal Corps constructed the Washington-Alaska Military Cable and Telegraph System (WAMCATS), also known as the Alaska Communications System (ACS). Contemporary accounts described this as among the first wireless telegraph systems in the Western Hemisphere.
In October 1903, Congress directed then Chief Signal Officer Brigadier General Adolphus Greely to issue an order. In October 1904, Congress appropriated $25,000 for the Signal Corps to "build a flying machine for war purposes" directing Chief Signal Officer Brigadier General Adolphus Greely to oversee the effort. Chief Signal Officer Brigadier General Adolphus Greely thus contracted the Wright brothers in 1908 to build and demonstrate a military airplane; the Wrights conducted their trials at Fort Myer, Virginia. Their historic first powered flight had taken place at Kitty Hawk, North Carolina, in December 1903.
On August 1, 1907, an Aeronautical Division was established under the Office of the Chief Signal Officer (OCSO). In 1908, in Fort Myer, Virginia, the Wright brothers conducted test flights of the Army's first airplane built to Signal Corps' specifications. Reflecting the need for an official pilot rating, War Department Bulletin No. 2, released on 24 February 1911, established a "Military Aviator" rating. Army aviation remained within the Signal Corps until 1918, when it became the Army Air Service.
During World War I, Chief Signal Officer George Owen Squier worked closely with private industries to perfect radio tubes while creating a major signal laboratory at Camp Alfred Vail (later Fort Monmouth). Early radiotelephones developed by the Signal Corps were introduced into the European theatre in 1918. While the new American voice radios were of higher quality than the radiotelegraph sets, the telephone and telegraph remained the major communication technology of World War I.
Also during World War I, women switchboard operators, known as the "Hello Girls," were sworn into the Signal Corps. Despite the fact that they wore U.S. Army uniforms and were subject to Army regulations (Chief Operator Grace Banker received the Distinguished Service Medal), they were not given honorable discharges but were considered "civilians" employed by the military, because Army regulations specified the male gender. Not until 1978—the 60th anniversary of the end of World War I—did Congress approve veteran status/honorable discharges for the surviving "Hello Girls."
A pioneer in radar, Colonel William Blair, director of the Signal Corps laboratories at Fort Monmouth, demonstrated the SCR-268 prototype in May 1937. Before the United States entered World War II, mass production of two radar sets, the SCR (Signal Corps Radio)-268 and the SCR-270, had begun.