Radio telegraphy
English submerged telegraph cables were pushed to the limits of the British Empire in the 1880s and 1890s, connecting the Foreign Office in London with the colonial governors in India, Africa, the Suez, and the Pacific. The wired connections allowed rapid response to situations as they arose and London was apprised of the colonial machinations of rivals Germany and France. Captains of the ships of the British Navy, formerly de facto ambassadors with extensive powers due to their isolation from the Admiralty, were able to consult with superiors while in port, rather than deal with crises on their own as had generations of their predecessors.
The British government was able to exert far more direct control over its possessions, and communicate directly with rival governments and allies. Many regions remained isolated, as connecting them to the submerged cable system was not cost effective, or they were too far away from the existing trunk lines. Many scientists and inventors studied ways of transmitting information using electricity to stations which were not connected by wires. Edison proposed a method of transmitting between ships using the water as the connecting medium. Tesla too studied wireless transmission, as did Hertz, Hughes, and Popov, but it was Guglielmo Marconi who developed, patented, and commercialized a wireless transmission of sound.
By 1898 Marconi was manufacturing radio transmitters and receivers in Chelmsford, England. His primary market was the maritime industry, equipping ships with what were called wireless sets, allowing them to communicate with each other and send and receive telegrams. Two years later a Brazilian priest first transmitted the human voice wirelessly over a distance of five miles. Rapidly developing technology, including the invention of the vacuum tube, allowed for the first commercial radio broadcast, made from the Massachusetts coast on Christmas Eve, 1906. Radio stations were born soon after.
Radio soon accommodated both radio-telegraphy and radio-telephone, allowing information to be broadcast and received in both coded messages and voice transmissions. Wireless communication crossed borders. Radio became an instrument for the spread of propaganda, news, entertainment, and culture. As technology expanded the power of transmitters, and thus the distance they could broadcast, leaders of nations could speak directly to the citizens of other nations inclined to listen. Government supervision of radio transmissions emerged in all nations, controlling who could broadcast and in some cases, including the United States, what could and could not be broadcast.
Most official government communications within themselves and between governments continued to use the submerged cables for security purposes, although wireless telegraphy of encoded messages expanded dramatically between the World Wars. The ability to intercept and decode the diplomatic and military messages of rival nations and allies became a critical aspect of national security. In 1919 the US government established the Black Chamber, the predecessor of the NSA, to monitor the diplomatic communications to and from the United States, leading Henry L. Stimson to later note with disdain that “Gentlemen do not read each other’s mail.”