Communications Surveillance during World War I

Two young telegraphers at the Main Telegraph Station in Copenhagen, app. 1915, deciphering a German telegram for a secret military intelligence unit called “Kystcentralen”


The dark and stormy circumstances of World War I, 1914–1918, prompted the development of government-backed regimes for mass surveillance of electric and postal communications across Europe. The transnational flows of information, which had expanded rapidly since the mid-nineteenth century, turned into a security risk at the outbreak of hostilities, as they were linked to escalating government fears of enemy propaganda, information leaks and espionage. Moreover, the war years saw the birth of modern signals intelligence, as demonstrated by the famous case of the ill-fated German Zimmermann Telegram.