The window of that room was the third along from the right on the second floor and I had naturally left it in darkness. I waited for more than an hour, drinking my schnapps slowly on the quayside. Another twenty minutes passed and then, to my relief and excitement, the light went on in my hotel window.

This was no visit by a maid, turning down the bed. The light remained on for over an hour, quite long enough for someone to photograph every page in the Secret Emergency War Code, as well as to search my effects and confirm my assumed identity as William Greville. Before they began the search, the intruders had allowed me time to get to the house where amusement might be found and to immerse myself in it. No doubt the hall porter was on guard at the desk, watching for any unexpected return, but they had every reason to believe that there was ample time in hand, more than enough to copy the bound cipher volume.

I waited for a little while after the light had gone off. Then I made my way to a restaurant near the famous statue of Erasmus and spent another hour or so eating my dinner. As for my return to the hotel, I have seen and heard enough drunkards during my career to put on a pantomime of being a little the worse for wear. I welcomed help from the kindly hall-porter in climbing the stairs and getting into bed. He was very insistent in seeing that I got there.

I tipped him generously and, as soon as he had gone, went to look for the attaché-case. It was once again under the pile of clothes but not quite as I had left it. Moreover, someone in closing it had caused it to lock automatically. Such was the end of my three days of active service in the pay of British Military Intelligence. I cannot pretend that I found it exciting, it was more than anything tedious and a matter of waiting around for something to happen. However, Holmes seemed well pleased with the result and Sir John Fisher appeared positively affable towards me.

5

For more than six months after this, Admiral Hall and his colleagues were able to transmit messages from our own chain of wireless stations in a code which the Germans could decipher, thanks to the present I had made them, but which meant nothing to our own side. All the same, this advantage was only to be exploited with great care.

Counterfeit cipher messages must correspond in most details to subsequent events. It was the few significant variations which would plant false information in the intelligence bureau of the Wilhelmstrasse. On one occasion, at least, Admiral Beatty altered by two days the date on which he was to take the Home Fleet to sea on gunnery exercises, in order that this should verify the counterfeit version of the war code ciphers. It was a small price to pay for giving apparent authenticity to a masterpiece of deception.

On the basis of false information fed to Berlin through the counterfeit cipher tables my friend engineered what became known sardonically in Room 40 as “The Sherlock Holmes Invasion of Belgium.” This was at a time when detachments of our troops were being withdrawn from the Western Front to reinforce the expeditionary force to Salonika. As Holmes remarked, it seemed desirable that the Germans should be induced to withdraw units of their own troops in return.

In messages based on the new ciphers, the intelligence bureau of the Wilhelmstrasse was allowed to read an ingenious fiction of closely-guarded movements by our small naval craft on the eastern coast of England. Flat-bottomed boats of the kind used for landing troops on a sandy coast were being marshalled there. A further message contained an instruction to stop at short notice all cross-channel shipping between England and neutral Holland. The order would remain in force for a fortnight, so that merchant shipping should not compromise the movement of an invasion fleet on course for the coast of Belgium.

These enciphered orders, based upon the counterfeit code and its appendix, then revealed details of an imminent invasion of that coast, in the rear of the German army in France. It was gratifying that the enemy’s High Command diverted some 20,000 men to the defence of the Belgian sands and dunes along the North Sea. Little by little, the Admiralty’s orders to an imaginary invasion fleet were received in Berlin. The vessels would sail in three groups, from Harwich, from Dover, and from the mouth of the Thames. The command for the temporary prohibition of sea traffic to Holland was authorised, though not yet issued.

As a final persuasion of the truth of this story, a special edition of the Daily Mail was printed. This was done in consultation with Admiral Hall and the paper’s editor. It consisted of only twenty-four copies for sale in Holland, where it was routinely bought by German agents. The paper contained a front-page paragraph reporting “Great Military Preparations on the East Coast” and “Flat Bottomed Boats.” Within hours, this was followed by a further edition of the Mail with the whole story blacked out, as if the censor had intervened.

In order that the plan did not seem too easily revealed, it was allowed to appear that the author of the feature had got the wrong end of the stick, as Holmes put it, and that he believed the East Coast was being prepared against an attack by the Germans. Officers of the German High Command knew that they did not intend to invade Eastern England. Therefore they were bound to assume that the journalist had got the rumour wrong and that it must be the British who were going to attack Belgium. In the confusion, they had felt compelled to switch an entire division or so to the defence of the empty sands round Ostend.

Both sides were now changing ciphers with greater frequency, every day on the stroke of midnight. It was a race which Holmes was prepared to run. Before the end of the year, he penetrated the most complex of all, the German diplomatic code. This was, in truth, a gift from the Kaiser’s vice-consul in Persia. The unfortunate diplomat had fled in his pyjamas, abandoning his luggage, after witnessing a failed German attack on the Abadan oil pipeline. This paved the way for our final victory in “the war of ghosts and shadows.”

6

By the autumn of 1916, the neutral nations included Holland, Latin America and, most significantly, the United States. Many in the Admiralty and the War Office spoke wistfully of a new order of things. To put it plainly, they meant the entry of the United States into the war on the Allied side.

Homes “drudged” by day, as he called it, and read by night. Increasingly his thoughts seemed to be elsewhere. One evening, he was occupied by a history of the Russo-Japanese war of 1904, when Britain had backed Japan against Russian expansion in the Pacific. In the outcome, a primitive Asiatic nation had defeated a great European power.

I noticed later what Holmes had written in the margin.

“ Japan will remain our ally in the present war until she has acquired Germany ’s possessions in China and the Pacific. If ever the war should go against us, it will be in her interest to turn her eyes upon the possessions of Britain and the United States in the Far East.”

It was a cynical but not impossible conclusion.

A day or two later he was absorbed by John Reed’s account of the 1910 Mexican revolution, Insurgent Mexico. What had we to do with that? Mexico ’s recent history seemed to me no more than a chronicle of one tyrannical revolutionary succeeding another, by courtesy of Pancho Villa and his bandits. Next evening, while he was engaged at his work-table, I saw that he had jotted a note in the margin of this book as well. “ United States military strength 40,000. Three-quarters of these with General Pershing in Mexico or on the frontier.”

Anyone who read the newspapers knew how President Wilson had sent the U. S. Marines ashore at Vera Cruz. The USS Prairie had also intercepted the German cargo ship Ypringa. On board were 200 machine-guns and several tons of ammunition for Pancho Villa and Carranza’s troops, with thirty or forty German officers to train them. What had all that to do with Armageddon on the Western Front? I tried facetiousness.