Wartime cablegram regulations, Western Union, 1915|
Warshaw Collection of Business Americana, Archives Center National Museum of American History, Smithsonian Institution
As early as the 1850s, during the Crimean War, underwater cables were used to send orders to armies overseas. Cutting an enemy's cables became a standard military tactic. Until recent decades, cables were nearly impossible to tap, making them the safest way of sending secret communications in wartime.
|This graph represents communications traffic between the American embassy in London and the U.S. Department of State. During World War I (1914-18) and World War II (1939-45), the use of cablegrams skyrocketed. Letters could be intercepted; cables were more secure.|
Communications traffic: letter vs. cablegram|
From Vary T. Coates and Bernard S. Finn, A Retrospective Technology Assessment: Submarine Telegraphy, 1979