In 1871 Blackwood's Magazine published the anonymous story 'The Battle of Dorking' purporting to describe a German invasion of Britain. Subtitled 'Reminiscences of a Volunteer', this work was intended as a warning against British complacency in the wake of the Franco-Prussian War which established Germany as Britain's main military rival in Europe. Its realism, prophetic fiction masquerading as direct factual reporting, lay in the detail with which it described the confusion following the invasion and the confrontation between British and German forces near Box Hill. Its author, Sir George Tomkyns Chesney, stressed the total lack of preparedness on Britain's part, and peppered his narrative with morals: 'we became wise when it was too late'; 'there, across the narrow straits, was the writing on the wall, but we would not choose to read it.' The British fleet is too widely dispersed to pose any real obstacle to the invaders. The army is disorganised and misled by a rumour that the enemy has landed at Harwich when it actually starts the invasion at Worthing. As the literary historian I. F. Clarke points out, 'from 1871 onwards Chesney's story showed Europe how to manipulate the new literature of anxiety and belligerent nationalism'. This work initiated a series of novels dealing with invasion—it was clearly drawn on by H. G. Wells for The War of the Worlds, for instance—which stress strong or weak military points in a triumphant or catastrophic manner according to the demands of propaganda.

In the years immediately following the Boer War a whole series of articles ran in British periodicals which expressed anxiety about the rapid build-up of the German navy. The Morning Post reported that 'there is a menace growing up in the east which cannot be ignored' and the National Review led an anti-German campaign by whipping up fears of a naval invasion. Three particular aspects of recent developments in Germany received attention. First in priority was the fear of Britain losing naval supremacy, specifically in the North Sea. An ex-naval officer [Thomas B. Moody] writing in the Fortnightly Review in 1903, for instance, traces German Anglophobia back to the war with Denmark in 1864 and makes a plea for the establishment of an east coast naval base at Filey. In the Nineteenth Century for the previous year Archibald S. Hurd praises the unique foresight and thoroughness of the German naval acts, contrasting the conditions they create with the state of the British navy which seems hamstrung by irrelevant traditions. The expansion of the German navy was perceived as being fuelled by the 'rooted conviction that Germany must possess colonies almost at any price', in what 0. Eltzbacher saw as amounting to a national obsession. Eltzbacher was not by any means alone in treating a war between the two powers as a very real possibility: 'It is clear that the North Sea will be the theatre of war where our fate will be decided.' Expansion is also seen to be the result of the Pan-German movement which a writer in the Quarterly Review of 1902 explained as wanting 'nothing less than German dominion over the whole of Middle Europe, and more'. That 'more' could well include Holland because Rotterdam would possess prime strategic importance as a port situated at the mouth of the Rhine and confronting Britain.

It is vital to bear this atmosphere of suspicion and distrust in mind when trying to understand the particular impact which was made by Erskine Childers's novel The Riddle of the Sands when it was published in 1903. Childers had served as a volunteer in the Boer War and in 1903 held a clerkship in the House of Commons, neither of which would adequately explain the remarkable political awareness of the novel which reads like a resume of all the fears the British press was expressing of German expansion. The novel was 'edited' by Childers as a 'record of secret service recently achieved' and describes a yachting cruise made by two university friends from Schleswig through the recently constructed Kiel Canal and around the islands of East Frisia in the course of which they stumble across a rehearsal of an invasion of Britain. Childers combines two genres, the tale of adventure and the tale of detection, into an ostensible story of sight-seeing where astonishing discoveries are made. The two friends possess simple but contrasting characters. Carruthers is the narrator, skilled at German, ignorant of seamanship; Davies is the yachtsman and the one with formulated political opinions about German imperialism. Childers initially plays the one character off against the other until Davies has convinced Carruthers of the rightness of his views and then the two friends join forces to reveal exactly what is going on in the Frisian Islands. The narrative rests on a series of realisations by Carruthers: of German military planning in general, of the strategic importance of the Ems Estuary (dividing Germany and Holland), and then—the crowning insight—of what lies behind the pretence of doing salvage work off the island of Juist:

I was assisting at an experimental rehearsal of a great scene when multitudes of sea-going lighters, carrying full loads of soldiers, not half loads of coals, should issue simultaneously, in seven ordered fleets, from seven shallow outlets, and, under escort of the Imperial Navy, traverse the North Sea and throw themselves bodily upon English Shores.

The cruise which the two men make takes Carruthers from one moment of awareness to another.

The starting-point of the cruise in the novel is Flensburg on the eastern coast of Schleswig which had been under German administration since the 1860s. In the manuscript of the novel Childers was at pains to stress that the country was being held under a military occupation which the very buildings themselves resist. As Carruthers climbs the hill towards the site of a crucial battle between Danes and Germans the political layout of the town below becomes clear: 'higher up the hill in the newer and busier quarter German flags and German uniforms showed in still sharper contrast to the Danish element. The very cafes were hostile and distinct'. The place becomes a living embodiment of military oppression and Carruthers's sympathy immediately goes out to 'the unconquered spirit of the conquered province under the iron heel of Prussia'. Although Childers deleted both these passages, thereby toning down Carruthers's criticism of Germany, the novel nevertheless firmly retains an anti-Prussian perspective. Carruthers's reactions draw the reader's attention to Germany's colonising activities near Britain and his 'sight-seeing' mentions the sea-borne landings which led to the defeat of the Danes long before a possible analogy might be drawn with Britain.

The next important stage on the journey comes when the yacht passes through the Kiel Canal. Canal-building was a vital extension of Germany's naval effort since these artificial waterways broke the land barrier posed by Denmark and linked the Baltic with the North Sea. The other main canal referred to in the novel runs from the Ems to the Jade Estuary, cutting across the hinterland of East Frisia and offering a speedy passage to naval gunboats. When the yacht enters the Kiel Canal Carruthers sees the same warships as Childers himself saw when he sailed through it in the 1890s. The canal is revealed as a highway, a crucial artery in German communications:

Broad and straight, massively embanked, lit by electricity at night till it is lighter than many a Great London street; traversed by great war vessels, rich merchantmen, and humble coasters alike, it is a symbol of the new and mighty force which, controlled by the genius of statesmen and engineers, is thrusting the empire irresistibly forward to the goal of maritime greatness.

It is here that the political sophistication of the novel lies, in passages like this where the German landscape is read with an eye alert to the strategic importance of canals, rivers and all the channels running between the Frisian Islands. In 1910 Childers contributed a series of articles on yachting to the Times and in the piece entitled 'Cruising in German Frisia' (23 August) he stressed exactly this way of responding to the landscape:

To stand on some remote plateau of sand which the tide has laid bare in the midst of this wilderness [the Frisian coast] is to obtain a point of vantage unique of its kind in Europe. Far away at the head of the Jade is the great new naval base of Wilhelmshaven, the dynamic centre of Germany's 20th century Welt-politik. Up and down the fairways of the Weser and Elbe glide huge liners, cargo-steamers, and sailing-vessels from every quarter of the globe. At night the guiding lights for this great Knoten-punkt of traffic twinkle on the horizon, the vivid wheeling beams from Heligoland dominant in the north; while the southern sky glows faintly over distant Hamburg and Bremen.

The description is charged with political implications in suggesting a military machine focused on the naval base, facilitated by the well-lit waterways, fed by great industrial centres, and guided by the beacons of Heligoland which Britain had handed over to Germany in 1890 in return for concessions in East Africa. The Riddle of the Sands takes a comparatively little-known area of coastline and ingeniously demonstrates its centrality to the German war effort. Childers's insights were confirmed by an anonymous contributor to Chamber's Journal in 1910 who drew attention to the further developments in the canal system and the opening new shipbuilding yards on the Ems and Weser. Even the livestock of the area has its role to play, since from East Frisia 'will come the horses for the German army if ever it invades England'. This writer, Childers and the other political commentators all take it more or less for granted that conflict between England and Germany is inevitable years before the First World War broke out.

By concentrating on the maritime implications of canal and rail networks and of inland waterways, Childers distinguished his own novel from other fictitious treatments of German aggression. Although The Riddle of the Sands extends the tactical insights of The Battle of Dorking, the point of view is different since Carruthers and Davies are looking towards England, as it were over German shoulders. Chesney's narrative makes its impact from being so firmly rooted in familiar home territory, as does Saki's later novel When William Came (1913) which describes Britain under German occupation. Childers also avoided the sensational gimmickry of William Le Queux's Invasion of 1910 (written with the support of Field-Marshal Lord Roberts and serialised in the Daily Mail in 1906) which carried fictitious proclamations addressed to the subjects of the occupying forces. Childers was a keen reader of Rudyard Kipling (referring in his novel to the latter's nautical terminology) who had been making statements about the German peril from the 1890s onwards. In 1897, for instance, Kipling pointed out the danger of war to Charles Norton, declaring: 'we are girded at and goaded by Germany'. Once war actually broke out, Kipling's anti-German feelings reached their peak and in 1916 he wrote to the Daily Express: 'One thing we must get into our thick heads is that whenever the German man or woman gets a suitable culture to thrive in he or she means death and loss to civilized people'. There is no suggestion in The Riddle of the Sands of such sweeping racial hostility, although Childers's novel bears directly on a story Kipling wrote in 1913 about the threat of invasion. 'The Edge of the Evening' (collected in A Diversity of Creatures) describes a gathering at a country house near the Channel. A plane—German, as it turns out—lands in the grounds of the house and is found to contain maps and aerial photographs clearly relating to a planned invasion. Childers also raises the possibility of Germans spying in England through the main personal antagonist of Davies and Carruthers, one Dollman who had served in the British navy and who now seems to be masquerading as a German officer. Dollman, it seems, has been spying around Chatham dockyard but when confronted by Childers's heroes claims to be a British agent. The ambiguity is erased when he takes the gentlemanly way out, of flinging himself overboard as the two are escaping with him to Holland. Personal antagonists have a symbolic role in this novel which is summed up in the original 1903 frontispiece. This depicts Kaiser Wilhelm in aggressive posture being confronted by a British opponent in an attitude of defence, his face set with determination. In 1916 Kipling published a volume of tributes (Sea Warfare) to the crews of British submarines, trawlers and destroyers which included, appropriately enough, an acknowledgement of Childers's technical accuracy in The Riddle of the Sands.

Childers's novel concludes with what purports to be the transcription of a memorandum to the German government detailing a plan of invasion which would be launched from East Frisia and which would involve a landing on the coast of Lincolnshire. The plan was of such interest to the First Lord of the Admiralty, Lord Selborne, that he asked Naval Intelligence to report to him on its feasibility. The response was a detailed explanation of how impracticable such a scheme would be. Childers's novel was so close to contemporary events that as it was going to press he had to add a postscript explaining recent developments in the area of home defence. One of Davies's complaints was that Britain possessed no standing committee to watch over its defence, and in 1903 such a committee was established. The second point the novel makes again and again is that Britain is vulnerable because it possesses no naval base on its east coast. Following public demonstrations it was announced in March 1903 that a base would be built on the Firth of Forth, thereby reducing the likelihood of attack from the North Sea. The decision had been taken in secret much earlier, but its announcement coincided happily with the publication of The Riddle of the Sands. Davies's third scheme was to organise the hundreds of men who like himself were skilled at navigation into a naval reserve force. Childers noted in his postscript that the idea was receiving favourable consideration and soon after his novel appeared the Naval Volunteer Reserve was indeed set up.

In 1910 The Riddle of the Sands was realised in a startlingly direct way. On the night of 21 August Lieutenant V. R. Brandon was arrested on the Frisian island of Borkum and charged with taking flashlight photographs of the fortifications at Borkum and Wangeroog. Some time later Captain B. F. Trench of the R.N.L.I. was also arrested in Emden. When the room he had used in the Union Hotel was searched, a number of documents were discovered under his mattress which included photographs and maps of Kiel, Wilhelmshaven and other locations on the coast with the position of buoys marked, notes on the North Sea fortifications, and details of the Kiel Canal. The story which Trench and Brandon stuck to consistently throughout their trial in the imperial court at Leipzig was that they had been making a sailing tour of Kiel, Heligoland and East Frisia in a purely personal capacity. The prosecution attacked this account, questioning the two officers about a copy of the 'naval Baedeker' (an Admiralty guide to the coastlines of different countries) which they had with them, and alleged that they were undercover agents on the basis that they had been having regular communication through coded letters with an official named 'Reggie' who was identified as a personal friend of Brandon attached to Naval Intelligence. The fact that Brandon was serving in the hydrography section of the Admiralty only appeared to confirm the prosecution's case that he and Trench were collecting details about piers, depths, etc. which would be valuable for mounting landing operations. The sections of the trial relating to Borkum were held in camera, partly because on the night of Brandon's arrest new naval floodlights were being tried out. At one point in the proceedings a copy of Childers's novel was produced and the defendants asked if they knew the book. Trench did and Brandon caused laughter in court when he declared: 'Yes I have read it—three times'. In fact the novel was more deeply implicated than was made clear at that time. When Captain William Henry Hall took over Naval Intelligence prior to the Borkum case, he made a cruise round German ports which confirmed Childers's charge that the existing Admiralty charts were inadequate, so inadequate that The Riddle of the Sands was used as a source of information. To rectify that situation in May 1910 Hall gave Trench and Brandon leave to tour the German coast, especially the Frisian Islands. In the event the German authorities found the case proved and the two officers were sentenced to serve four years in a military fortress.

So much public interest was aroused by the Borkum case that Childers made a statement about it in the Daily News of 23 December, where he made a determined effort to stand back from partisan hysteria. The case, he implied, was an inevitable result of the very existence of armed forces:

Let this be thoroughly understood: as long as nations maintain armaments for purposes of war, so long, as a necessary corollary, must plans, as definite and detailed as possible, be made in advance by each nation for the eventuality of war.

Childers minimised the guilt of Trench and Brandon, arguing that their one culpable act was crossing a fence to examine gun-emplacements. Their activities repeated those of Davies and Carruthers in so far as they had simply observed what was visible to any traveller and had used maps and guidebooks on open sale

for the greatest part of the information in question is not a matter of esoteric mystery, but is easily accessible from ordinary maps, plans, charts, and books of reference which have a free international sale to any citizen of any country who wishes to obtain them.

Ironically, during the Borkum trial the prosecution tried to show that Britain was planning an invasion of Germany, no doubt with an eye to the current Anglophobia at home, whereas the very reverse was the case. Paul Kennedy has discovered a plan in the German military archives dating back to the 1890s which was very similar to that outlined in the epilogue to The Riddle of the Sands. Where Childers foresaw that lighters and barges would be used because of their shallow draught, the plan included steamers; and where he specified East Holland as the ideal landing-place on the Lincolnshire coast because it most closely resembled East Frisia, the German plan was directed against the coast of East Anglia. The scheme was first considered as early as 1896 but was shelved when Britain established a North Sea base.

Childers clearly intended his novel to have an effect on British naval policy and in 1906 wrote to Sir George Clarke of the Committee of Imperial Defence with a detailed memorandum on the north German coast. Among other things he proposed the construction of shallow vessels for easy loading, repeated the strategic importance of Borkum, and even suggested blocking the Kiel Canal. Unbeknown to him, Borkum was already being considered by the Committee as a possible target for invasion, but the plan was left aside until the First World War broke out, when Childers was invited to update his proposals. This he did in a document called 'The Seizure of Borkum and Juist' which found favour with Churchill but which was never put into action. The nearest Childers came to acting on his invasion plans was to participate in a Fleet Air Arm raid on Cuxhaven.

The Riddle of the Sands belongs to a period before Britain had a fully developed intelligence service, especially in the naval sphere. It now seems dated in its confidence that committed amateurs can function as efficiently as professionals, and yet the historical facts bear out Childers's general insights and confirm Davies's bluff assertion that 'those Admiralty chaps want waking up'. The reviewers recognised immediately that the book was written with a clear purpose in mind. In 1904 the Westminster Gazette explained rightly that 'it is meant to secure our national safety, and to increase the prospects of peace by making greater the risks to be faced by any nation which may contemplate the invasion of these islands'. The fact that it was immediately banned in Germany and just as quickly adopted by the Admiralty for inclusion in naval libraries only goes to show the accuracy of Childers's narrative.