Mr Varney had vowed to do anything for Holmes in return. Several months ago, he had redeemed this pledge by infiltrating the office of Posts and Telegraphs in Mexico City. Under revolutionary law, coded telegrams were forbidden for fear that they might be used to start yet another revolution. However, the government minister responsible frequently permitted commercial codes to escape scrutiny, in exchange for a small bribe. Mr Varney, in his turn, had been able to bribe a lesser functionary. This man would alert him to the texts of incoming Western Union telegrams from Count Bernstorff in Washington to Minister Eckhardt at the German Mission in Mexico City.
“It is simple enough,” said Holmes, next morning at the breakfast table. “The United States Embassy in Berlin may forward German telegrams to the State Department in Washington—and so to the German Embassy. However, the State Department will not forward them to the German Minister in Mexico City. In any case, there is nothing beyond Galveston except the services of Western Union. Mr Varney is able to confirm that such telegrams are passing to Herr Eckhardt. They are in code, but any coded texts in the archives of Western Union in Mexico City will henceforward be available to us. Perhaps we shall no longer be working blindfold after all.”
Within days there came into our hands at Baker Street, late one afternoon, a wire from Mr Varney. It had been forwarded by courtesy of Captain Guy Gaunt, the British Naval Attaché in Washington, who was also Naval Intelligence officer at the embassy. This wire accompanied the secret message which is known to history as the “Zimmermann Telegram”—and which the reader will find quoted as a coded text at the opening of this chapter. What follows is the best sense that Sherlock Holmes and I could make of it that evening.
We sat at either side of the work-table while Holmes made two copies of the coded message and passed one to me. I hardly knew how to start upon it but the keen energy of my friend’s brain began to illuminate the darkness of the cipher like forked lightning.
“Let us dispose of the first two groups of numbers, Watson. At the start, 130 is simply the number of the telegram and tells us nothing. The next, 13042, is the current prefix for communications in the German diplomatic code and tells us a good deal. Then you will see 13401, which identifies its source as the German Foreign Office, not the embassy in Washington. The source, if not the message, is genuine. The next item, 8501, confirms that this began its journey as a ‘Most Secret’ telegram from Berlin to Count Bernstorff, who has now forwarded it to Mexico City. Between them, such clues narrow our area of search a little.”
“We have intercepted no messages between Berlin and Washington in the past fortnight,” I said cautiously, “May this not be a hoax of some kind by the German intelligence service?”
He frowned and ran his pencil across the rows of numbers.
“I think not,” he said presently, “By its number this is a recent telegram which Zimmermann has passed to Bernstorff under the cover of the United States diplomatic code. Had Bernstorff not forwarded it to Mexico City, we should never have seen it. I believe that disposes of any hoax. Now then, there are recurring words in this cipher and I fancy they will show us the way”
His pencil was busy for a moment. Then he looked up.
“The framework of the telegram is in a cipher system we have encountered before, therefore what follows must be related to it. The message, I concede, appears to be encrypted according to a new code, that is the challenge, but the system which sustains it should be the same.”
He pushed his paper across to me.
“See here. In the preliminary instructions, we have 17214, which has previously been used for
ganz geheim-strictly
secret. Well that is no surprise—it is an old friend to me. And then, here, 6491 11310 18147. That is also familiar from previous use. Selbst
zu entziffern
—
decipher
this yourself. From there on the code has been varied and everything is a little opaque.”
I worked my way through it, trying to pick out any groups of letters whose position or repetition might help us to “get a lever” under the rest. Holmes took another approach.
“We know that Eckhardt in Mexico City must be able to decode it. It has been sent as a matter of urgency and therefore probably in a code that can be read by anyone who knew the previous one. Eckhardt is not allowed to refer the matter to his underlings, he can ask for no assistance, therefore it must be a familiar system to him.”
He bowed his head over the paper, the harsh white gaslight throwing the shadow of his aquiline profile on the wall. Presently he chuckled. His pencil was ticking the most frequently used words. He selected one of them.
“Here, here, and here, Watson. The group of numbers most frequently used is 69853. From its position, as compared with earlier messages which we have decrypted, it appears to be a noun, almost certainly a proper name. In an urgent and secret diplomatic message to the German Minister in Mexico City, what is that word likely to be?”
“I would say most probably ‘Mexico.”’
“And here it is used with the cipher 5870, which also occurs just before it and immediately after it. The same 5870 occurs again two words further on. May I be kicked from here to Charing Cross if that is not a comma! What else can it be with such frequency? Now, such a series of commas would suggest a list, would it not? A list of three items in this case, the second of which is in two words. The second of those two words is ‘Mexico.’ So we have a compound noun, the second half of which is ‘Mexico.’ To me that strongly suggests ‘New Mexico.’ Let us see.”
It was a characteristic leap of intuition. Beforehand the answer might have appeared an outside possibility. As presented by Holmes, it now seemed the only answer that made sense.
“In all probability it is a list of American states,” I said quickly.
“Excellent, Watson. New Mexico, with an item before and an item after. The one in front of it appears as five letters. Try “Texas.” The one that follows it has four syllables. What state associated with Texas and New Mexico has four syllables?”
“Arizona?” I replied hopefully.
“And what unites Texas, New Mexico, Arizona? All three were at one time part of Mexico and were lost to the United States by conquest. What plan has Herr Zimmermann for those states now?”
“To return them to Mexico? Impossible!”
“Not at all impossible, provided that there is a sufficient bargain upon the table. Another name 52262 recurs closely. You will recall that all nations in the last diplomatic cipher to be broken by us were reduced to five digits and I fancy this is one of them. Allow me the luxury of supposing that it stands for “Japan.” You will recall that the battle-cruiser
Asuma
lately paid a prolonged courtesy call to Mexico, as the papers tell us. That news was contained in one of Bernstorffs previous ‘appreciations’ of the war situation. The ship was in Turtle Bay so long that she ran aground and had to be attended by other units of the Japanese fleet.”
“What about the United States?” I inquired cautiously, “Surely a more likely country to be mentioned than Japan in the context of Mexico?”
“Not quite in the proximity which we find here. If my instinct is right, this telegram is about the part to be played by others in respect of the United States. In that case, ‘United States’ may have a lower frequency than the protagonists. You will find 39695, here, and here, and here, occurring almost incidentally. That I deduce is more likely to be the United States. I shall be surprised if I am not right.”
We worked long into that cold January night, deaf to the sounds of the street below, indifferent to the supper which Mrs Hudson brought on a tray and which remained untasted.
“Yes, yes!” said Holmes impatiently to her kindly reproach. Presently the sitting-room air was clouded with the smoke of his pipe and the food still remained almost untouched.
I was little help, I fear. Yet I could not have torn myself away as I watched him working at the blocks of numbers on the telegram form. He had the previous cipher of the German diplomatic telegrams to hand and now established to his own satisfaction the five-number groups which represented the nations, like pieces on a chess-board.
As the hours passed, Zimmermann’s text began to appear in groups or clumps of letters and signs, like islands in a sea of numbers. Just after midnight, Holmes hit another vein of inspiration. Nouns were divided into groups of four or five letters. Other words varied a little to identify each occurrence. He made out that 6926, 6929 and 6992, were varying forms of “and,” determined by which letter began the next word. This in turn gave him the first letters of “Japan,” “understanding” and “suggestion.” With fewer than half the words deciphered, the purpose of the telegram was plain. He recognised 5903 as “krieg” or “war.” A repetition of 98092 from an earlier telegram gave him “U-boat.” This left him with an incomplete phrase, “ersten 13605 un-14963 U-boot krieg.”
“What is the date, Watson?”
I was quite unprepared for this and had to think for a moment.
“The twenty-third of January. That is to say, the small hours of the twenty-fourth.”
“Admirable! Then the crucial date in the telegram must be ‘ersten Februar’—the first of February! The first of the next month in the immediate future. One does not use telegrams for dates that are far off, there is no urgency and the decision may not yet have been taken. Therefore we have, The first of February un-14963 U-boat war.’ There is already a U-boat war being fought but what is to come is in some way different. What can that be but ‘The first of February un-restricted U-boat war.’ It is an instruction to Bernstorff in Washington and an order to Eckhardt in Mexico City, to the effect that Germany will sink on sight, in a week’s time, neutral shipping entering European waters.”
“Wilson cannot hold back from war, if that is the case!”
“I fear he may. The decision lies with Tirpitz and his master. If the Germans use the threat sparingly, Wilson will hesitate to commit his country to all-out war. Who would not? The loss of a few ships is nothing compared to a million men slaughtered on the battlefield and the nation’s prosperity in ruins. In any case, the likely outcome is that neutral vessels will keep well away from our shores, our own merchant fleet will be destroyed by Germany’s torpedoes, and our goose will be cooked. That is the plan in Berlin. They want to preserve peace with America, if they can. If not, they hope to trap her in a war on her own continent.”
By three o’clock in the morning his pessimism seemed confirmed. We now had a translation of the text of the earlier passage: “Zimmermann to Bernstorff. Strictly Secret. Decipher this yourself. We intend to begin unrestricted U-boat warfare from 1 February. We will attempt to keep the United States BLANK. If this should not be BLANK, we offer Mexico....”
“The first BLANK is ‘neutral’” I said, “the second is ‘possible.’”
The rest of that night was spent in teasing out from the sets of numbers just what it was that Mexico might be offered in exchange for a German alliance. We made out “united in war, united in peace.” Then we returned to “Texas, New Mexico, Arizona” and the single word “zuruck”—“back.” Preposterous though it might seem, President Carranza was being offered the return of Mexico’s lost territories in return for loyalty to the Kaiser.
This reading was confirmed when Holmes deciphered the two occurrences of 22464 as “President,” referring to President Carranza of Mexico, who was to be both a German ally and mediator in the alliance. He must induce 52262—Japan—to join the pact. England, which now appeared for the first time, would be “compelled” to make peace in a few months by a massive U-boat assault now being prepared. This would be sustained by supplies and fuel from Mexican ports. So long as the United States had only its small peacetime army, it could be invaded along the Mississippi valley by a Mexican army with the support of German “legionaries” and Japanese troops, conveniently cutting off those territories which were now to be returned to President Carranza. It was a complete confirmation of the tall story I had heard in the Army and Navy Club several years before!
I burst out laughing at the apparent absurdity of the suggestion. Holmes remained solemn.
“You cannot take it seriously,” I said, “the notion of the Japanese occupying the Mississippi Valley!”
“What I take seriously, Watson, is that America is strong at sea but weaker on land, as England has been. Such have been both our historic priorities. I take seriously the prospect of a small American peacetime army fighting valiantly, suffering reverses at first, but eventually being victorious. Pending that eventuality, which may be months or years away, I also take seriously the probable triumph of the U-boat campaign, while the Tampico oil wells supply German submarine bases in Mexico. I take seriously the choking of our supply lines by U-boat fleets, stalemate on the Western Front, the Royal Navy starved of fuel oil, immobilised, and a peace treaty leaving Germany with all her European conquests.”
“What a peace!” I said, as if to myself.
“Belgium would be her puppet state, giving her a seaboard opposite our own shores. France would lose all that she lost in the war of 1871 and more besides. Morocco would be a German colony, opposite Gibraltar. Remember the German gunboat
Panther’s
seizure of Agadir in the crisis of 1911.”