It was obvious from the outbreak of World War I in 1914 that wireless had become a technology of great strategic importance. The British government immediately took control of parts of the Marconi company, such as its latest transatlantic stations in Wales and its factory in Chelmsford, and the company established an ambitious training programme for wireless operators. While government restrictions meant that public developments were suspended, the demands of war – from land, sea and airborne services – meant that other technical developments were accelerated.
Wartime priorities emphasised the potential for counter-offensive inherent in wireless communication – signals could be intercepted, for example, and direction-finding techniques could locate the positions of enemy transmitters. Once it was possible to locate trench wireless sets, enemy troop positions could also be known, as well as Zeppelins and other hostile aircraft. It was detection of wireless traffic that alerted the British navy to the movements of the German fleet and precipitated the Battle of Jutland in May 1916.