‘The Bruce-Partington Plans’, in which the design of a new and devastating type of submarine is stolen from Woolwich Arsenal and sold to a foreign spy, came at an ominous moment in British history. When it was first published in the December 1908 issue of the Strand Magazine, the war that would consume Conan Doyle's attention – and several members of his family – was still more than five years away. But Germany had already become Britain's principal geopolitical adversary: Britain entered strategic ententes with France (1904) and Russia (1907), alliances which would endure into – and help precipitate – the First World War; a naval arms race, centred on Dreadnought-class battleships but including the new, disruptive technologies of submarines and torpedoes, was in full swing; and Germany was widely believed to be conducting espionage in Britain on an unprecedented scale.

Britain at this time became gripped by what historians now call ‘spy fever’: vast numbers of German agents, often posing as waiters or barbers, were believed to be diligently collecting intelligence on coastal defences, roads and railways, and the strength and disposition of the armed forces: for example, in 1908 Lord Roberts, Britain's most highly decorated war hero, announced to Parliament that Germany had infiltrated 80,000 trained soldiers into the British Isles. What was remarkable about this moral panic was not just that it was so exaggerated, but that it largely derived from fiction. As well as conjuring fears of the shape of wars to come, invasion-scare fiction also developed into the genre of espionage fiction which, after the First World War, supplanted it in British popular culture. Kipling's Kim (1901), which tells how an Irish street urchin in Lahore becomes one of British Intelligence's most valuable agents in its cold war with the Russian Empire, is often credited as a foundational text of the genre, along with the late-imperial romances of John Buchan which updated the adventure fiction of imperial expansion with the geopolitical tensions of an age of imperial contestation. But as David Stafford has shown, it was William Le Queux, E. Phillips Oppenheim and others of their ilk who developed many of the tropes and themes that now seem so familiar from spy fiction.